Hank Murrow on wed 2 apr 08
On Apr 2, 2008, at 5:52 PM, Ingeborg Foco wrote:
> Hello Vince,
>
> I hope your are reading the list. I bought my flap wheel - 80 grit
> from
> Grainger. Installed it and had it working. Much to my dismay, it
> works
> great in grinding off the bottoms but leaves very dark "burnt" spots
> wherever you touch it to the pot. The dark burned spots are very
> hard to
> remove but I was able to sand them off with an 80 grit sandpaper
> and a lot
> of elbow grease. Kinda defeats the purpose!
Dear Ingeborg;
I have had the same trouble on white clays. It seems to be the binder
that holds the grit on the cloth flaps. I have been asking around of
different manufacturers to see if I might find a flap wheel that does
not mark the clay. No luck as yet.
Cheers, Hank
Ingeborg Foco on wed 2 apr 08
Hello Vince,
I hope your are reading the list. I bought my flap wheel - 80 grit from
Grainger. Installed it and had it working. Much to my dismay, it works
great in grinding off the bottoms but leaves very dark "burnt" spots
wherever you touch it to the pot. The dark burned spots are very hard to
remove but I was able to sand them off with an 80 grit sandpaper and a lot
of elbow grease. Kinda defeats the purpose!
What am I doing wrong? Looking for inputs and thanking you in advance.
--
Sincerely,
Ingeborg
www.thepottersworkshop.com
John Britt on thu 3 apr 08
After a trip to the Homer Laughlin China Company, I started using a
surface conditioning pad from 3M, 120 mesh industrial grade that Mike
Tkach showed me.
I hooked it to a bat with some velcro and it really makes the bottoms
nice. As an added treat, I squirted on some water based valve grinding
compound, which I usually use for lids because they make such a nice sound
after you grind them, and man, oh, man. Smooth as Tony's ...well it is way
smooth.
John Britt
www.johnbrittottery.com
Vince Pitelka on thu 3 apr 08
Ingebord wrote:
"I hope your are reading the list. I bought my flap wheel - 80 grit from
Grainger. Installed it and had it working. Much to my dismay, it works
great in grinding off the bottoms but leaves very dark "burnt" spots
wherever you touch it to the pot. The dark burned spots are very hard to
remove but I was able to sand them off with an 80 grit sandpaper and a lot
of elbow grease. Kinda defeats the purpose!"
Ingebord -
Either you bought an inferior flap wheel, or you are using it wrong. You
say that you are using it for grinding off the bottoms, and that's not what
it's good for. A flap wheel works well for smoothing the bottoms of pots
with a very light touch. A grinding wheel is for grinding, and the
difference between the two is pretty obvious. Once you have finished
grinding off glaze runs and residue with the grinding wheel, you use the
flap wheel to polish the surface, again with a very light tough. On pots
that do not have any glaze runs or residue on the bottom but just have a
slightly rough surface, a light once-over with the flap wheel will give you
a silky smooth surface.
Your comment that the flap wheel is leaving dark burnt spots indicates to me
that you are really leaning into it, and that's completely improper use of
the flap wheel, and will wear it out in no time.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Nobody Special on thu 3 apr 08
On Wed, 2 Apr 2008 20:52:30 -0400, Ingeborg Foco
wrote:
>Hello Vince,
>
>I hope your are reading the list. I bought my flap wheel - 80 grit from
>Grainger. Installed it and had it working. Much to my dismay, it works
>great in grinding off the bottoms but leaves very dark "burnt" spots
>wherever you touch it to the pot. The dark burned spots are very hard to
>remove but I was able to sand them off with an 80 grit sandpaper and a lot
>of elbow grease. Kinda defeats the purpose!
>
>What am I doing wrong? Looking for inputs and thanking you in advance.
>
>--
>Sincerely,
>
>Ingeborg
>
The burnt spots are indeed the melted resin binder from the sandpaper. The
melting is caused by the heat generated from excess friction. The easiest
fix is to use much, much, much less pressure against the wheel. Use a very
light touch and let the abrasive do the work rather than pressure. These
wheels are made for wood or soft metals, both of which generate much less
heat than does dense ceramic.
If your grinder is multi-speed, slow it way down. Most bench grinders run
at either 1725 or 3450 RPM. 3450 is really too fast for the job you are doing.
Hope it helps.
...James
pdp1@EARTHLINK.NET on fri 4 apr 08
Hi Ingeborg,
Might be you have already eroded most of the agragate...and or, that the RPM
is too high for the kind of Flap-Wheel it is...
Is your Motor 3,500 RPM? verses 1,750?
Just-a-thought...
Phil
l v
----- Original Message -----
From: "Ingeborg Foco"
> Sorry for the flap over flap wheels :) I admit Vince, I was really
> leaning into the flap wheel. I don't know if I bought an inferior wheel
> but
> I bought it at Grangers and suspect it is operator error.
>
> Today I tried to do the easy touch and could see and feel the difference,
> somewhat but...one wrong move and a brown/burned spot again. All I can
> guess is there is a learning curve to this bottom smoothing.
>
> Hank, what do you do for your bottoms since the flap wheel didn't work out
> for you either?
>
> Ingeborg
> www.thepottersworkshop.com
Vince Pitelka on fri 4 apr 08
The flap wheel that Ingebord purchased from Grainger's is the one I told her
to buy, and the same model I have been using for fifteen years. We do a lot
of salt, soda, and wood firing here at the Craft Center, and thus the clay
has a lot of color. The slight residue (Ingebord and others called it "burn
marks")left by the flap wheels never bothered us at all, but I can see how
some people firing whiteware or porcelain might have a problem with those
marks. I really do not have any suggestion for that, other than to use some
of the other grinding media recommended by Clayart members.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Hank Murrow on fri 4 apr 08
On Apr 4, 2008, at 4:36 PM, Ingeborg Foco wrote:
> Sorry for the flap over flap wheels :) I admit Vince, I was really
> leaning into the flap wheel. I don't know if I bought an inferior
> wheel but
> I bought it at Grangers and suspect it is operator error.
>
> Today I tried to do the easy touch and could see and feel the
> difference,
> somewhat but...one wrong move and a brown/burned spot again. All
> I can
> guess is there is a learning curve to this bottom smoothing.
>
> Hank, what do you do for your bottoms since the flap wheel didn't
> work out
> for you either?
Dear Ingeborg;
I still have not found one that won't leave a mark despite Vince's
directions for use. What I wound up relying on was foam backed
diamond pads. These are plastic sheets with dots of diamond grit from
70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
around $50 and they last a long time if used carefully with water to
carry the waste away, so I do it in the sink. It takes around two
hours to clean up and polish the bottoms, etc. from one firing in my
28 cuft kiln.
I purchase them from Master Supply in Seattle: http://
www.masterwholesale.com/
And these are the ones: http://www.masterwholesale.com/details/
1122498368.html
Lots on this page: http://www.masterwholesale.com/shop/Polishing-
Pads-(Handheld).html
Cheers, Hank, still looking for a flap wheel that doesn't mark the ware.
Ingeborg Foco on fri 4 apr 08
Sorry for the flap over flap wheels :) I admit Vince, I was really
leaning into the flap wheel. I don't know if I bought an inferior wheel but
I bought it at Grangers and suspect it is operator error.
Today I tried to do the easy touch and could see and feel the difference,
somewhat but...one wrong move and a brown/burned spot again. All I can
guess is there is a learning curve to this bottom smoothing.
Hank, what do you do for your bottoms since the flap wheel didn't work out
for you either?
Ingeborg
www.thepottersworkshop.com
On Thu, Apr 3, 2008 at 8:36 PM, Vince Pitelka wrote:
> Ingebord wrote:
> "I hope your are reading the list. I bought my flap wheel - 80 grit from
> Grainger. Installed it and had it working. Much to my dismay, it works
> great in grinding off the bottoms but leaves very dark "burnt" spots
> wherever you touch it to the pot. The dark burned spots are very hard to
> remove but I was able to sand them off with an 80 grit sandpaper and a lot
> of elbow grease. Kinda defeats the purpose!"
>
> Ingebord -
> Either you bought an inferior flap wheel, or you are using it wrong. You
> say that you are using it for grinding off the bottoms, and that's not
> what
> it's good for. A flap wheel works well for smoothing the bottoms of pots
> with a very light touch. A grinding wheel is for grinding, and the
> difference between the two is pretty obvious. Once you have finished
> grinding off glaze runs and residue with the grinding wheel, you use the
> flap wheel to polish the surface, again with a very light tough. On pots
> that do not have any glaze runs or residue on the bottom but just have a
> slightly rough surface, a light once-over with the flap wheel will give
> you
> a silky smooth surface.
>
> Your comment that the flap wheel is leaving dark burnt spots indicates to
> me
> that you are really leaning into it, and that's completely improper use of
> the flap wheel, and will wear it out in no time.
> - Vince
>
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka@dtccom.net; wpitelka@tntech.edu
> http://iweb.tntech.edu/wpitelka
>
>
> ______________________________________________________________________________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here:
> http://www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
>
--
Sincerely,
Ingeborg
www.thepottersworkshop.com
jonathan byler on fri 4 apr 08
Ingeborg,
What exactly did you get for a flap wheel again? grainger part #
would be good start. Given all the various types available, and
sizes to boot, I would imagine that some materials used as
substrates, binders, and or abrasives might not be compatible with
the stuff you are grinding. The burned spots may be the binder from
the sandpaper on the flap wheel heating up and melting into the pores
of the fired ceramic piece. I have found when grinding down drips on
kiln shelves with a ridged masonry type grinding wheel on an angle
grinder that it can heat up the glaze drips to the point of glowing,
and that it is invariably accompanied by an acrid smell, which
implies to me that either the grinding wheel, the glaze, or both are
burning.
Depending on the diameter flap wheel that you are using and the RPM's
of your grinder (bench or hand held, btw?), you might just have the
wheel moving to fast for the material you are cutting. To slow down
the cutting, try getting a smaller flapwheel, which will cut down
your SFM and the heat created by sanding. you might find that to get
a good surface that you need a progression of grits, much like with
sanding wood or metal, and to use some sort of wet sander/grinder to
keep the heat down.
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 4, 2008, at 6:36 PM, Ingeborg Foco wrote:
> Sorry for the flap over flap wheels :) I admit Vince, I was really
> leaning into the flap wheel. I don't know if I bought an inferior
> wheel but
> I bought it at Grangers and suspect it is operator error.
>
> Today I tried to do the easy touch and could see and feel the
> difference,
> somewhat but...one wrong move and a brown/burned spot again. All
> I can
> guess is there is a learning curve to this bottom smoothing.
>
> Hank, what do you do for your bottoms since the flap wheel didn't
> work out
> for you either?
>
> Ingeborg
> www.thepottersworkshop.com
>
> On Thu, Apr 3, 2008 at 8:36 PM, Vince Pitelka
> wrote:
>
>> Ingebord wrote:
>> "I hope your are reading the list. I bought my flap wheel - 80
>> grit from
>> Grainger. Installed it and had it working. Much to my dismay, it
>> works
>> great in grinding off the bottoms but leaves very dark "burnt" spots
>> wherever you touch it to the pot. The dark burned spots are very
>> hard to
>> remove but I was able to sand them off with an 80 grit sandpaper
>> and a lot
>> of elbow grease. Kinda defeats the purpose!"
>>
>> Ingebord -
>> Either you bought an inferior flap wheel, or you are using it
>> wrong. You
>> say that you are using it for grinding off the bottoms, and that's
>> not
>> what
>> it's good for. A flap wheel works well for smoothing the bottoms
>> of pots
>> with a very light touch. A grinding wheel is for grinding, and the
>> difference between the two is pretty obvious. Once you have finished
>> grinding off glaze runs and residue with the grinding wheel, you
>> use the
>> flap wheel to polish the surface, again with a very light tough.
>> On pots
>> that do not have any glaze runs or residue on the bottom but just
>> have a
>> slightly rough surface, a light once-over with the flap wheel will
>> give
>> you
>> a silky smooth surface.
>>
>> Your comment that the flap wheel is leaving dark burnt spots
>> indicates to
>> me
>> that you are really leaning into it, and that's completely
>> improper use of
>> the flap wheel, and will wear it out in no time.
>> - Vince
>>
>> Vince Pitelka
>> Appalachian Center for Craft
>> Tennessee Tech University
>> vpitelka@dtccom.net; wpitelka@tntech.edu
>> http://iweb.tntech.edu/wpitelka
>>
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here:
>> http://www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>>
>
>
>
> --
> Sincerely,
>
> Ingeborg
>
> www.thepottersworkshop.com
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
jonathan byler on sat 5 apr 08
How big is this flap wheel? 3450 rpm is very fast for sandpaper
applications, depending on the size of the wheel of course. I would
think that you might have less trouble on a grinder that spins at
1725 rpm using the same size wheel, although that still might not
solve everything. Nothing quite beats wet grinding when doing
lapidary type work.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 5, 2008, at 5:04 AM, Ingeborg Foco wrote:
>>
>>
>>> Dear Hank,
>>
>>
>
> My bench grinder runs at 3450 RPM if I remember correctly.
> Presently I use
> a sharpening stone to grind the bottoms of the pots. It is a
> stone used to
> sharpen lawn and garden tools when people did those kind of things
> instead
> of throwing them away. It works quite well but one kiln load takes
> me close
> to two days to smooth. I just thought there must be an easier
> way. Thanks
> for the link, it looks like a good way to go.
>
> Are you doing Showcase this year? I am planning on going so maybe
> I'll see
> you.
>
> Ingeborg
>
>
>
> Dear Ingeborg;
>
> I still have not found one that won't leave a mark despite Vince's
> directions for use. What I wound up relying on was foam backed
> diamond pads. These are plastic sheets with dots of diamond grit from
> 70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
> around $50 and they last a long time if used carefully with water to
> carry the waste away, so I do it in the sink. It takes around two
> hours to clean up and polish the bottoms, etc. from one firing in my
> 28 cuft kiln.
>
> I purchase them from Master Supply in Seattle: http://
> www.masterwholesale.com/
>
> And these are the ones: http://www.masterwholesale.com/details/
> 1122498368.html
>
> Lots on this page: http://www.masterwholesale.com/shop/Polishing-
> Pads-(Handheld).html
>
> Cheers, Hank, still looking for a flap wheel that doesn't mark the
> ware.
>
>>
>>
>>
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
Ingeborg Foco on sat 5 apr 08
>
>
> > Dear Hank,
>
>
My bench grinder runs at 3450 RPM if I remember correctly. Presently I use
a sharpening stone to grind the bottoms of the pots. It is a stone used to
sharpen lawn and garden tools when people did those kind of things instead
of throwing them away. It works quite well but one kiln load takes me close
to two days to smooth. I just thought there must be an easier way. Thanks
for the link, it looks like a good way to go.
Are you doing Showcase this year? I am planning on going so maybe I'll see
you.
Ingeborg
Dear Ingeborg;
I still have not found one that won't leave a mark despite Vince's
directions for use. What I wound up relying on was foam backed
diamond pads. These are plastic sheets with dots of diamond grit from
70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
around $50 and they last a long time if used carefully with water to
carry the waste away, so I do it in the sink. It takes around two
hours to clean up and polish the bottoms, etc. from one firing in my
28 cuft kiln.
I purchase them from Master Supply in Seattle: http://
www.masterwholesale.com/
And these are the ones: http://www.masterwholesale.com/details/
1122498368.html
Lots on this page: http://www.masterwholesale.com/shop/Polishing-
Pads-(Handheld).html
Cheers, Hank, still looking for a flap wheel that doesn't mark the ware.
>
>
>
Kenneth D. Westfall on sat 5 apr 08
A sanding drum used for lapidary work which has water dripping over it to
keep it cool works great for smoothing off the bottom of any kind of clay
with no burn marks. The belts are silicon carbide grit in a 400 to 800
grit work nicely. You can then switch to a hard flat felt polishing wheel
and tin oxide to do a real high glossy finish if you feel you need
to. Water that keeps it all cool in the main thing to not have burnt marks.
Richard Aerni on sat 5 apr 08
Hank,
I too use the flap wheel that Vince recommended, and find that if it is used
a microsecond too long, it leaves marks on my white stoneware as well.
However, if used lightly, it is enough. I do everything possible to not
leave "stuff" on my pot bottoms that needs grinding, so mostly I'm just a
quick 10 second rotation of the pot on the wheel and it's done. So, I'm not
sure I want to spend 4 hours per kiln firing with your diamond paper, but I
will check the info and file it away...thanks for that!
What I do to keep the gribblies off my pots is to use alumina wax on the
bottoms first (don't have kiln wash on my shelves), and then whenever
possible, fire the pots either on a soft brick pancake (cut about 1/4-1/2
inch thick from soft bricks with a sharp drywall saw) or on alumina rolled
wads, if the bottom is too broad for the pancake. I rarely have "bits" on
the bottoms.
Take care...
Richard Aerni
Rochester, NY
On Fri, 4 Apr 2008 22:29:03 -0700, Hank Murrow wrote:
>
>Dear Ingeborg;
>
>I still have not found one that won't leave a mark despite Vince's
>directions for use. What I wound up relying on was foam backed
>diamond pads. These are plastic sheets with dots of diamond grit from
>70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
>around $50 and they last a long time if used carefully with water to
>carry the waste away, so I do it in the sink. It takes around two
>hours to clean up and polish the bottoms, etc. from one firing in my
>28 cuft kiln.
>
>I purchase them from Master Supply in Seattle: http://
>www.masterwholesale.com/
>
>And these are the ones: http://www.masterwholesale.com/details/
>1122498368.html
>
>Lots on this page: http://www.masterwholesale.com/shop/Polishing-
>Pads-(Handheld).html
>
>Cheers, Hank, still looking for a flap wheel that doesn't mark the ware.
>
John Post on sat 5 apr 08
Hi Ingeborg,
I took Hank's suggestion on the diamond pads and ordered just one of
them. I got the 400 grit.
It works well on my cone 6 Tucker's white clay body. Like Hank, I too
rinse the residue out of the pad at the sink. The one pad cost around
$14 total to have it shipped to my house. The weird thing about their
website is that you place your order, but then they call you the next
day to get your credit card number. They aren't set up for secure
payment over the web.
John Post
Sterling Heights, Michigan
http://www.johnpost.us :: cone 6 glaze website ::
http://www.wemakeart.org :: elementary art website ::
> What I wound up relying on was foam backed
> diamond pads. These are plastic sheets with dots of diamond grit from
> 70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
> around $50
Hank Murrow on sat 5 apr 08
On Apr 5, 2008, at 7:42 AM, John Post wrote:
>
> I took Hank's suggestion on the diamond pads and ordered just one of
> them. I got the 400 grit.
> It works well on my cone 6 Tucker's white clay body. Like Hank, I too
> rinse the residue out of the pad at the sink.
Say, just to prevent confusion, the pads are solid, not squishy, so
one is washing the residue off the diamond-impregnated surface. The
foam block is rigid, and does not absorb water.
> The one pad cost around
> $14 total to have it shipped to my house. The weird thing about their
> website is that you place your order, but then they call you the next
> day to get your credit card number. They aren't set up for secure
> payment over the web.
I use the 70, 120, 220, 400, & 600 grits, the last is very fine. If
you go to the 3500 grit you can really polish the bottoms shiny like
terrazzo. And it should be mentioned that these cut with only very
light pressure..... the diamond does the work.
Cheers, Hank
Ron Roy on wed 9 apr 08
I keep waiting for someone to include a warning about using flap wheels - I
can't think of a better way to put lots of fine silica into the air.
I hope you all are doing this sort of thing out side and up wind.
RR
>How big is this flap wheel? 3450 rpm is very fast for sandpaper
>applications, depending on the size of the wheel of course. I would
>think that you might have less trouble on a grinder that spins at
>1725 rpm using the same size wheel, although that still might not
>solve everything. Nothing quite beats wet grinding when doing
>lapidary type work.
>
>
>jon byler
>3-D Building Coordinator
>Art Department
>Auburn University, AL 36849
>
>On Apr 5, 2008, at 5:04 AM, Ingeborg Foco wrote:
>
>>>
>>>
>>>> Dear Hank,
>>>
>>>
>>
>> My bench grinder runs at 3450 RPM if I remember correctly.
>> Presently I use
>> a sharpening stone to grind the bottoms of the pots. It is a
>> stone used to
>> sharpen lawn and garden tools when people did those kind of things
>> instead
>> of throwing them away. It works quite well but one kiln load takes
>> me close
>> to two days to smooth. I just thought there must be an easier
>> way. Thanks
>> for the link, it looks like a good way to go.
>>
>> Are you doing Showcase this year? I am planning on going so maybe
>> I'll see
>> you.
>>
>> Ingeborg
>>
>>
>>
>> Dear Ingeborg;
>>
>> I still have not found one that won't leave a mark despite Vince's
>> directions for use. What I wound up relying on was foam backed
>> diamond pads. These are plastic sheets with dots of diamond grit from
>> 70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
>> around $50 and they last a long time if used carefully with water to
>> carry the waste away, so I do it in the sink. It takes around two
>> hours to clean up and polish the bottoms, etc. from one firing in my
>> 28 cuft kiln.
>>
>> I purchase them from Master Supply in Seattle: http://
>> www.masterwholesale.com/
>>
>> And these are the ones: http://www.masterwholesale.com/details/
>> 1122498368.html
>>
>> Lots on this page: http://www.masterwholesale.com/shop/Polishing-
>> Pads-(Handheld).html
>>
>> Cheers, Hank, still looking for a flap wheel that doesn't mark the
>> ware.
>>
>>>
>>>
>>>
>>
>> ______________________________________________________________________
>> ________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here: http://
>> www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>
>______________________________________________________________________________
>Clayart members may send postings to: clayart@lsv.ceramics.org
>
>You may look at the archives for the list, post messages, change your
>subscription settings or unsubscribe/leave the list here:
>http://www.acers.org/cic/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at melpots2@visi.com
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
jonathan byler on wed 9 apr 08
yes, agreed.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 9, 2008, at 12:56 AM, Ron Roy wrote:
> I keep waiting for someone to include a warning about using flap
> wheels - I
> can't think of a better way to put lots of fine silica into the air.
>
> I hope you all are doing this sort of thing out side and up wind.
>
> RR
>
>> How big is this flap wheel? 3450 rpm is very fast for sandpaper
>> applications, depending on the size of the wheel of course. I would
>> think that you might have less trouble on a grinder that spins at
>> 1725 rpm using the same size wheel, although that still might not
>> solve everything. Nothing quite beats wet grinding when doing
>> lapidary type work.
>>
>>
>> jon byler
>> 3-D Building Coordinator
>> Art Department
>> Auburn University, AL 36849
>>
>> On Apr 5, 2008, at 5:04 AM, Ingeborg Foco wrote:
>>
>>>>
>>>>
>>>>> Dear Hank,
>>>>
>>>>
>>>
>>> My bench grinder runs at 3450 RPM if I remember correctly.
>>> Presently I use
>>> a sharpening stone to grind the bottoms of the pots. It is a
>>> stone used to
>>> sharpen lawn and garden tools when people did those kind of things
>>> instead
>>> of throwing them away. It works quite well but one kiln load takes
>>> me close
>>> to two days to smooth. I just thought there must be an easier
>>> way. Thanks
>>> for the link, it looks like a good way to go.
>>>
>>> Are you doing Showcase this year? I am planning on going so maybe
>>> I'll see
>>> you.
>>>
>>> Ingeborg
>>>
>>>
>>>
>>> Dear Ingeborg;
>>>
>>> I still have not found one that won't leave a mark despite Vince's
>>> directions for use. What I wound up relying on was foam backed
>>> diamond pads. These are plastic sheets with dots of diamond grit
>>> from
>>> 70 grit to 1600 grit. I use ones from 70 to 600 grit. The set runs
>>> around $50 and they last a long time if used carefully with water to
>>> carry the waste away, so I do it in the sink. It takes around two
>>> hours to clean up and polish the bottoms, etc. from one firing in my
>>> 28 cuft kiln.
>>>
>>> I purchase them from Master Supply in Seattle: http://
>>> www.masterwholesale.com/
>>>
>>> And these are the ones: http://www.masterwholesale.com/details/
>>> 1122498368.html
>>>
>>> Lots on this page: http://www.masterwholesale.com/shop/Polishing-
>>> Pads-(Handheld).html
>>>
>>> Cheers, Hank, still looking for a flap wheel that doesn't mark the
>>> ware.
>>>
>>>>
>>>>
>>>>
>>>
>>> ____________________________________________________________________
>>> __
>>> ________
>>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>>
>>> You may look at the archives for the list, post messages, change
>>> your
>>> subscription settings or unsubscribe/leave the list here: http://
>>> www.acers.org/cic/clayart/
>>>
>>> Moderator of the list is Mel Jacobson who may be reached at
>>> melpots2@visi.com
>>
>> _____________________________________________________________________
>> _________
>> Clayart members may send postings to: clayart@lsv.ceramics.org
>>
>> You may look at the archives for the list, post messages, change your
>> subscription settings or unsubscribe/leave the list here:
>> http://www.acers.org/cic/clayart/
>>
>> Moderator of the list is Mel Jacobson who may be reached at
>> melpots2@visi.com
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
Nobody Special on wed 9 apr 08
On Wed, 9 Apr 2008 00:56:21 -0500, Ron Roy wrote:
>I keep waiting for someone to include a warning about using flap wheels - I
>can't think of a better way to put lots of fine silica into the air.
>
>I hope you all are doing this sort of thing out side and up wind.
>
>RR
>
Ron...
I have been laboring under the notion (quite possibly another passed along
clay "fact" that is not a fact)that it is only free silica that is a health
problem, and that once the clay is fired the vast majority of any free
silica that was present is now chemically bound. Is this not the case?
...James
pdp1@EARTHLINK.NET on wed 9 apr 08
Hi Ron, all...
Seems so to me also.
Personally, I would think that using 'wet' ( likely 'Silicon Carbide' type )
Abrasive Papers, by 'hand', literally in and or immediately above a pan or
tub of Water, dipping often, would be more prudent, if a little
slower...and, would thus encourage more care in one's use of Glazes or
design of Pot
Feets, in order to enjoy less 'sanding' and so on.
But yes, a high RPM 'Flap Wheel' I think would be well calculated to cause a
long duration airborne suspension of ultra fine aspirable Silica-type
particles which will both get into one's clothing to be re-suspended as one
move about later, as well as to settle slowly on surfaces and floors to
likewise
be re-suspended in the Air as one walk or move about or open a Door or admit
a Breeze or whatever...so...
Maybe not-so-good...
Wearing a 'mask' merely during the operation of running a 'Flap Wheel' of
course may tend to overlook the fine particle's airborne leisures continuing
long and or intermittently when re-disturbed after settling, after one is
done with the actual operation proper,
where, typically, one would remove their mask for the rest of the day and
thereafter.
So...
Personally, I would not use a Flap wheel for addressing Ceramic surfaces
'dry',
for those reasons, even though I understand the advantage of it's
flexibility to conform to those surfaces' particular shapes.
Used out of Doors, with circumspect as for prevailing Breeze, 'maybe' would
be alright-enough...
If 'Wet-and Dry' versions are made, then of course one could run it indoors
or out of Doors, with a small thin stream of mildly Soapy Water, with a low
Curtain with hand holes in it to save one's clothing from the resulting
off-spray, being careful to see that the run off is collected or not allowed
to get too messy ( where once dry it could become airborne if walked on or
disturbed) , and be doing about as well as possible then in these regards.
Phil
l v
----- Original Message -----
From: "Ron Roy"
>I keep waiting for someone to include a warning about using flap wheels - I
> can't think of a better way to put lots of fine silica into the air.
>
> I hope you all are doing this sort of thing out side and up wind.
>
> RR
Ron Roy on sun 13 apr 08
Hi James,
There is always some free silica in a clay body - well 99.9 percent of the
time anyway - plus - what wiuld be the material glued to the flaps - sand?
Probably - so it is getting shattered as well - the breaking up of silica
is the real problem - those sharp edges are what cut up lung tissue.
RR
>On Wed, 9 Apr 2008 00:56:21 -0500, Ron Roy wrote:
>
>>I keep waiting for someone to include a warning about using flap wheels - I
>>can't think of a better way to put lots of fine silica into the air.
>>
>>I hope you all are doing this sort of thing out side and up wind.
>>
>>RR
>>
>
>Ron...
>
>I have been laboring under the notion (quite possibly another passed along
>clay "fact" that is not a fact)that it is only free silica that is a health
>problem, and that once the clay is fired the vast majority of any free
>silica that was present is now chemically bound. Is this not the case?
>
>...James
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Nobody Special on mon 14 apr 08
On Sun, 13 Apr 2008 16:30:50 -0500, Ron Roy wrote:
>Hi James,
>
>There is always some free silica in a clay body - well 99.9 percent of the
>time anyway - plus - what wiuld be the material glued to the flaps - sand?
>
Ron...
The grit on the sandpaper is aluminum oxide. Wet/dry paper is silicon
carbide. Cheaper sandpaper is often garnet. I don't think you can even
find flint paper any more. Haven't seen it since I was a kid. It wore out
too fast. (I have been a woodworker for a long time).
BTW, I personally don't power sand my pots. I hand sand with 180 grit.
Then again, I don't make nearly the number of pieces the rest of you do.
All the best.
...James
John Britt on mon 14 apr 08
Ron,
I am pretty sure that "sand" paper is not really sand. What I have is
alumina oxide or silicon carbide. So that is not shattering.
Also, I teach all my students to wear a respirator when sanding or
grinding. So even if it were sand they wouldn't be breathing it in.
Finally, I thought that it was the free silica or molecular silica that
was the worst because it got deep into your lungs.
John Britt
www.johnbrittpottery.com
Vince Pitelka on tue 15 apr 08
John Britt wrote:
"Finally, I thought that it was the free silica or molecular silica that
was the worst because it got deep into your lungs."
John -
My understanding is that it is not a matter of the finest silica particles
getting deeper into the lungs. There is nothing to prevent any of the
silica particles from getting deep into the lungs if we breath them. In
other words, if they are small enough to be airborne and a person breathes
them, they will get deep in the lungs. As I understand it, the cilia on the
inside surface of a healthy lung can expel the coarser silica particles
(they move them up into the bronchial passages, where the coughing reflex is
initiated), but they cannot handle the finest ones, which simply remain in
place, and the lung tissue reacts by growing nodules of scar tissue around
them. If this goes on long enough, the result is greatly diminished lung
capacity and some variation of silicosis.
This has nothing to do with your comment, but it is always worth including
in this conversation. The cilia on the inside surface of the lung are
disabled by smoking, and thus the smokers lungs loose the capacity to expel
ANY of the silica particles.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Steve Slatin on wed 16 apr 08
Vince --
Well it's certainly the case that
anything that's in the air can be
inhaled, and that the particles
inhaled are handled differently.
I'd also agree completely with
your comment on smoking.
There's lots of epidemiological
evidence that smoking alone
does much less harm than
smoking plus extensive exposure
to particular particles.
And the way the body handles
inhaled particles does seem to
differ based on the size of
the particles.
There is some evidence, however,
that the type of silica makes a
difference as well. This issues is
somewhat complicated by the
fact that certain types of
silica molecules are typically
larger or smaller than other
types.
IIRC, the crystalline form
particles are generally 'under
5 microns' in size. The amorphous
particle size is considerably smaller
(like two orders of magnitude, I
believe).
There may be a type of silica
-- or a size of silica -- that can be
readily absorbed across the lung's
tissue. When it does so, though,
it may be involved in cytokine
reactions. The link below leads
to an article in Particle and Fibre
Toxicology that may be interesting
(or not!).
Cytokines are involved in immune
reactions, embryonic development,
and maybe some other things.
-- Steve Slatin
Vince Pitelka wrote:
John Britt wrote:
"Finally, I thought that it was the free silica or molecular silica that
was the worst because it got deep into your lungs."
John -
My understanding is that it is not a matter of the finest silica particles
getting deeper into the lungs. There is nothing to prevent any of the
silica particles from getting deep into the lungs if we breath them. In
other words, if they are small enough to be airborne and a person breathes
them, they will get deep in the lungs. As I understand it, the cilia on the
inside surface of a healthy lung can expel the coarser silica particles
(they move them up into the bronchial passages, where the coughing reflex is
initiated), but they cannot handle the finest ones, which simply remain in
place, and the lung tissue reacts by growing nodules of scar tissue around
them. If this goes on long enough, the result is greatly diminished lung
capacity and some variation of silicosis.
---------------------------------
Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now.
Ron Roy on thu 17 apr 08
Phil said -
>Wearing a 'mask' merely during the operation of running a 'Flap Wheel' of
>course may tend to overlook the fine particle's airborne leisures continuing
>long and or intermittently when re-disturbed after settling, after one is
>done with the actual operation proper,
>where, typically, one would remove their mask for the rest of the day and
>thereafter.
It's a good point and we should all understand how long the fine silica
that causes silicosis can remain airbourn.
I had a call from a teacher many years ago - high school - could not work
anymore because he got silicosis in a classroom situation. He was being
denied compensation on top of it all. He would not give me all the details
but I did believe him - I've seen some of the conditions in class rooms -
the surprising thing is that more don't get sick from the dust and fumes.
RR
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Paul Haigh on thu 17 apr 08
With regards to particle size, in making biological weapons, it's known that the 1-10 micron range is targeted because they tend to stick in the lungs well and do all those wonderful things that they do. 4 microns turns out to be the sweet spot. Too large- they don't make it in, too small, they are more easily expelled and don't necessarily settle between breaths (remain suspended in any laminar flow).
Could be different for silica, but I seem to remember this was the general rule for all airborne materials
Paul Haigh
Londonderry, NH
Ron Roy on sun 20 apr 08
I think you are right about the sand part but your students would have to
wear the masks all the time to avoid the dust in the air if inside.
As I said - there is free silica in clay bodies - even in porcelain - it
shows up on a dilatometer chart at 573C.
You can see it in our book in the section on Glaze fit.
RR
>Ron,
>
>I am pretty sure that "sand" paper is not really sand. What I have is
>alumina oxide or silicon carbide. So that is not shattering.
>
>Also, I teach all my students to wear a respirator when sanding or
>grinding. So even if it were sand they wouldn't be breathing it in.
>
>Finally, I thought that it was the free silica or molecular silica that
>was the worst because it got deep into your lungs.
>
>John Britt
>www.johnbrittpottery.com
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Ron Roy on sun 20 apr 08
Hello again James -
Not trying to badger anyone but are there any heath concerns with aluminium
oxide, silicon carbide or garnet?
Do any of these materials get reduced to finer particles when used on a
flap wheel?
RR
>>Hi James,
>>
>>There is always some free silica in a clay body - well 99.9 percent of the
>>time anyway - plus - what wiuld be the material glued to the flaps - sand?
>>
>
>Ron...
>
>The grit on the sandpaper is aluminum oxide. Wet/dry paper is silicon
>carbide. Cheaper sandpaper is often garnet. I don't think you can even
>find flint paper any more. Haven't seen it since I was a kid. It wore out
>too fast. (I have been a woodworker for a long time).
>
>BTW, I personally don't power sand my pots. I hand sand with 180 grit.
>Then again, I don't make nearly the number of pieces the rest of you do.
>
>All the best.
>
>...James
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Nobody Special on sun 20 apr 08
On Sun, 20 Apr 2008 16:52:32 -0500, Ron Roy wrote:
>Hello again James -
>
>Not trying to badger anyone but are there any heath concerns with aluminium
>oxide, silicon carbide or garnet?
>
>Do any of these materials get reduced to finer particles when used on a
>flap wheel?
>
>
Ron...
I don't know of any health concerns with common abrasives, but I'm sure
everything can kill us in some way or other.
The abrasives used for sandpaper are significantly harder than the objects
they are intended to abrade. Garnet is an aluminosilicate (at least the
common varieties) with a hardness of 7-7.5 on the Moh scale. Aluminum
oxide, also sometimes called corundum in it's gem form, has a hardness of 9.
Silicon carbide, sometimes called carborundum, has a hardness of 9-10. For
reference, diamond has a hardness of 10, talc 1, and feldspar 6. Glass is
6-7, and a knife blade is about 6.5-7.
By contrast, vitrified stoneware typically has a hardness of about 7, though
YMMV. As such, the grit on the sandpaper is not abraded or reduced to dust
by the stoneware, but the stoneware IS abraded and reduced to dust by the
much harder grit.
Also, the grit on sandpaper does not get "worn down" in the conventional
sense. The individual grains do not get smoothed or rounded through use.
Rather, the grains fracture in use, thereby exposing fresh sharp edges.
Sandpaper is "worn out" when the grains have either fractured to a size too
small for further work, or have become dislodged from the resin binder.
Having said this, and as I mentioned earlier, I personally do not power sand
my pots. I find that a couple of quick swirls by hand around the foot ring
with 180 grit aluminum oxide paper does just fine, and with minimal risk of
scratching the adjacent glaze.
Hope this helps.
...James
jonathan byler on mon 21 apr 08
ron,
when reading MSDS sheets for alumina hydrate, I didn't see any
information about chronic respiratory problems as I did regarding
products containing silica. plaster that does not contain portland
cement is also supposed to only be a nuisance dust, not a cause of
chronic problems. take from that what you will.
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 20, 2008, at 4:52 PM, Ron Roy wrote:
> Hello again James -
>
> Not trying to badger anyone but are there any heath concerns with
> aluminium
> oxide, silicon carbide or garnet?
>
> Do any of these materials get reduced to finer particles when used
> on a
> flap wheel?
>
> RR
>
>
>>> Hi James,
>>>
>>> There is always some free silica in a clay body - well 99.9
>>> percent of the
>>> time anyway - plus - what wiuld be the material glued to the
>>> flaps - sand?
>>>
>>
>> Ron...
>>
>> The grit on the sandpaper is aluminum oxide. Wet/dry paper is
>> silicon
>> carbide. Cheaper sandpaper is often garnet. I don't think you
>> can even
>> find flint paper any more. Haven't seen it since I was a kid. It
>> wore out
>> too fast. (I have been a woodworker for a long time).
>>
>> BTW, I personally don't power sand my pots. I hand sand with 180
>> grit.
>> Then again, I don't make nearly the number of pieces the rest of
>> you do.
>>
>> All the best.
>>
>> ...James
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
Ron Roy on mon 21 apr 08
Hi James,
One more question - with quartz it's the sharp edges that are the problem -
rounded sand does not produce the same condition. If the aluminium oxide,
silicon carbide and garnet are sharp as well why would they not produce the
same injury to lungs?
Anyone else know the answer?
RR
>On Sun, 20 Apr 2008 16:52:32 -0500, Ron Roy wrote:
>
>>Hello again James -
>>
>>Not trying to badger anyone but are there any heath concerns with aluminium
>>oxide, silicon carbide or garnet?
>>
>>Do any of these materials get reduced to finer particles when used on a
>>flap wheel?
>>
>>
>Ron...
>
>I don't know of any health concerns with common abrasives, but I'm sure
>everything can kill us in some way or other.
>
>The abrasives used for sandpaper are significantly harder than the objects
>they are intended to abrade. Garnet is an aluminosilicate (at least the
>common varieties) with a hardness of 7-7.5 on the Moh scale. Aluminum
>oxide, also sometimes called corundum in it's gem form, has a hardness of 9.
> Silicon carbide, sometimes called carborundum, has a hardness of 9-10. For
>reference, diamond has a hardness of 10, talc 1, and feldspar 6. Glass is
>6-7, and a knife blade is about 6.5-7.
>
>By contrast, vitrified stoneware typically has a hardness of about 7, though
>YMMV. As such, the grit on the sandpaper is not abraded or reduced to dust
>by the stoneware, but the stoneware IS abraded and reduced to dust by the
>much harder grit.
>
>Also, the grit on sandpaper does not get "worn down" in the conventional
>sense. The individual grains do not get smoothed or rounded through use.
>Rather, the grains fracture in use, thereby exposing fresh sharp edges.
>Sandpaper is "worn out" when the grains have either fractured to a size too
>small for further work, or have become dislodged from the resin binder.
>
>Having said this, and as I mentioned earlier, I personally do not power sand
>my pots. I find that a couple of quick swirls by hand around the foot ring
>with 180 grit aluminum oxide paper does just fine, and with minimal risk of
>scratching the adjacent glaze.
>
>Hope this helps.
>
>...James
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
jonathan byler on mon 21 apr 08
I am no expert, but It was always explained to me that particle size
is what is important. the other materials can get breathed back out,
but that the silica particles get so small that they are trapped deep
in the alveoli, and stay put. It was only recently that I had heard
the the silica particles actually cut and scar your lungs. My
understanding of asbestos, was that it has little hooks that catch on
your lung tissue and that the lung tissue scars and also envelopes it.
is there a doctor in the house?
if silica is so bad, (which I believe that it is) do people who live
in sandy deserts such as the middle east have higher incidences of
silicosis?
jon
jon byler
3-D Building Coordinator
Art Department
Auburn University, AL 36849
On Apr 21, 2008, at 6:22 PM, Ron Roy wrote:
> Hi James,
>
> One more question - with quartz it's the sharp edges that are the
> problem -
> rounded sand does not produce the same condition. If the aluminium
> oxide,
> silicon carbide and garnet are sharp as well why would they not
> produce the
> same injury to lungs?
>
> Anyone else know the answer?
>
> RR
>
>> On Sun, 20 Apr 2008 16:52:32 -0500, Ron Roy
>> wrote:
>>
>>> Hello again James -
>>>
>>> Not trying to badger anyone but are there any heath concerns with
>>> aluminium
>>> oxide, silicon carbide or garnet?
>>>
>>> Do any of these materials get reduced to finer particles when
>>> used on a
>>> flap wheel?
>>>
>>>
>> Ron...
>>
>> I don't know of any health concerns with common abrasives, but I'm
>> sure
>> everything can kill us in some way or other.
>>
>> The abrasives used for sandpaper are significantly harder than the
>> objects
>> they are intended to abrade. Garnet is an aluminosilicate (at
>> least the
>> common varieties) with a hardness of 7-7.5 on the Moh scale.
>> Aluminum
>> oxide, also sometimes called corundum in it's gem form, has a
>> hardness of 9.
>> Silicon carbide, sometimes called carborundum, has a hardness of
>> 9-10. For
>> reference, diamond has a hardness of 10, talc 1, and feldspar 6.
>> Glass is
>> 6-7, and a knife blade is about 6.5-7.
>>
>> By contrast, vitrified stoneware typically has a hardness of about
>> 7, though
>> YMMV. As such, the grit on the sandpaper is not abraded or
>> reduced to dust
>> by the stoneware, but the stoneware IS abraded and reduced to dust
>> by the
>> much harder grit.
>>
>> Also, the grit on sandpaper does not get "worn down" in the
>> conventional
>> sense. The individual grains do not get smoothed or rounded
>> through use.
>> Rather, the grains fracture in use, thereby exposing fresh sharp
>> edges.
>> Sandpaper is "worn out" when the grains have either fractured to a
>> size too
>> small for further work, or have become dislodged from the resin
>> binder.
>>
>> Having said this, and as I mentioned earlier, I personally do not
>> power sand
>> my pots. I find that a couple of quick swirls by hand around the
>> foot ring
>> with 180 grit aluminum oxide paper does just fine, and with
>> minimal risk of
>> scratching the adjacent glaze.
>>
>> Hope this helps.
>>
>> ...James
>
> Ron Roy
> 15084 Little Lake Road
> Brighton, Ontario
> Canada
> K0K 1H0
>
> ______________________________________________________________________
> ________
> Clayart members may send postings to: clayart@lsv.ceramics.org
>
> You may look at the archives for the list, post messages, change your
> subscription settings or unsubscribe/leave the list here: http://
> www.acers.org/cic/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots2@visi.com
Nobody Special on tue 22 apr 08
On Mon, 21 Apr 2008 18:22:13 -0500, Ron Roy wrote:
>Hi James,
>
>One more question - with quartz it's the sharp edges that are the problem -
>rounded sand does not produce the same condition. If the aluminium oxide,
>silicon carbide and garnet are sharp as well why would they not produce the
>same injury to lungs?
>
>
Ron...
I am certainly not a doctor, so can only relate my limited understanding of
silicosis. I would speculate that it is for much the same reason that kids
don't get silicosis from playing in a sandbox.
It is my understanding that silicosis is caused by the inhalation of
sub-micron sized particles of crystalline free silicon dioxide. Larger
particles do not make it to the little aveoli in the lungs. This presents
three areas where sanding dust would not meet the criteria.
First, none of the modern sanding media are silicon dioxide, as the old
flint paper was. They are all aluminosilicates, so it is my understanding
of chemistry that the silica is bound, not free.
Second, the minerals used for grit are amorphous, not crystalline. If they
were crystalline, they would not fracture into sharp edges (conchoidal
fracture), so would not cut terribly well. Think of flint knapping, or the
way in which glass chips.
Lastly, the fractured bits of grit are, relatively speaking, very large and
heavy. I would speculate that most of the bits are much too heavy to float
in the air, and much too large to lodge in an aveola. The dust from the
ground media, however, could definitely be small enough to float in the air,
and would present an inhalation risk.
To the extent the clay body being ground contains crystobalite, a
crystalline form of silicon dioxide, I think there would be a risk. I would
offer, however, that this risk is likely tiny compared to the constant
inhalation of clay dust in a typical studio situation.
A fourth thought is that if, indeed, there was even the remotest hint of
speculation that some form of even theoretical lung damage could proceed
from sandpaper use, then some trial lawyer would long ago have crafted a
contrived class action lawsuit and enriched himself by extorting money out
of "Big Sandpaper".
Again, I personally don't power sand ceramics, and typically wear a dust
mask even when power sanding wood, but even if I did, it would be near the
bottom of the ceramic-related health risks that I worry about. Constant low
dose exposure to clay dust in the studio is definitely at the top of my
personal list. Manganese exposure falls about 97 orders of magnitude below
this one on my personal worry list, and everything else barely registers.
Disclaimer (the fast talk at the end of the commercial that no one can
understand):
I am not a doctor nor a scientist, and am offering no advice. These
statements represent only my own thoughts and understanding, and are not to
be relied upon in making your own health or occupational decisions. In
short, everyone needs to do their own research on the many and various
health risks related to ceramics in general and this topic in particular,
and make their own informed decisions.
All the best.
...James
Ron Roy on tue 22 apr 08
Hi Jon,
Desert sand is rounded so they get a different kind of effect - I think I
remember - not so dangerous.
RR
>I am no expert, but It was always explained to me that particle size
>is what is important. the other materials can get breathed back out,
>but that the silica particles get so small that they are trapped deep
>in the alveoli, and stay put. It was only recently that I had heard
>the the silica particles actually cut and scar your lungs. My
>understanding of asbestos, was that it has little hooks that catch on
>your lung tissue and that the lung tissue scars and also envelopes it.
>
>is there a doctor in the house?
>
>if silica is so bad, (which I believe that it is) do people who live
>in sandy deserts such as the middle east have higher incidences of
>silicosis?
>
>jon
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
pdp1@EARTHLINK.NET on wed 23 apr 08
Hi Ron, all...
Far as I recall...
'Desert' Sands, whatever their origin to begin with, are vastly too large
anyway, whatever their surface texture or cleavage planes...and the Aeolian
or incidental and occasional Alluvial
forces acting on them, do not admit velocities or pressures sufficient to
fracture the 'grains' into further or minute particles for them to be
sufficiently apspirable to be of concern.
There is in effect, no comparison on any basis between the occasionally Wind
blown Sands of Desert regions, and, the 'dusts' produced in the use of
Grinding Wheels, Flap Wheels, Abrasive Belts or Discs...nor are these Sands
able to be suspended in still Air.
The model I recall, representing the aetiology of 'Silicosis', is that
minute particles ( of many things, not only ostensible Silica per-se ) if
managing to
lodge deeply enough into the sub-brachiated minutiae of a Lung's vast
network
of tiny surfaces within tunnels... if not soluble to the chemistry
'there', will simply confuse the Body as for what
to do with it, what to do with the foreign insoluble 'particle'...
So, if it may not be floated out on mucous, or dissolved, it will be
encapsulated and
sealed off, rather loosely parallel to what an Oyster is understood to do
using Calcium Carbonate
with a 'grain' of anything 'foreign' which gets lodged in it's tender self,
making, in an Oyster's case of course, a 'Pearl'.
Nothing is 'cutting' or 'hooking' mechanically on anything on the scale of
events in our Lungs with
respect to Silica or other ultra minute particles, no matter what shape they
are...and, the Lungs do not care if the item is 'Silica' or a thousand other
possible things which it regards as 'foreign', insoluble and confusing.
Tuberculosis, similarly, is not a condition which results from a foreign
Organism doing anything hostile or destructive, rather, it is the result of
the Body's, or the Lung's reaction, or over-reaction, or an auto-immune
over-re-action, to what in fact is a
benign and of course minute Bacteria Creature who accidentally stumbled in
on
the ( interior ) 'winds'.
Probably, the same is going on with 'Silica' - where, it is not that Silica
is per-se intrinsically inimical or insulting or hostile to the Organ, but,
rather, that there is a confused or ill-prepared response-mechanism for
evicting it, or a
response mechanism which lacks insight and viable solution for it, and the
mechanism of response if the 'problem'.
And that it is the relative 'lightness' of some kinds of minute particles or
fibres, which allow them to be suspended in the Air, in order for them to be
aspirated, or, aspirated deeply enough to be brought into the
sub-brachiation's attenuations in the Lungs, which is the deciding
'mechanism' of their being deemed 'dangerous'.
Nothing is 'hooking' on anything, nothing is 'cutting' anything.
Asbestos, when macerated or pulverized with enough vigor or exuberance or
otherwise caused to release ultra
minute fibres or filaments...( and only then )
Coal 'dust'...when 'fine' enough...
Rock 'dusts'...ditto...
Wood 'dusts'...ditto...
Wheat Flour 'dusts'...ditto...
Organic or other Fertilizer 'dusts'...ditto..
'Dusts' period when 'small' enough, no matter what their provenance...will
potentially invite problems.
Anything, when physically amenable by virtue of it's structure, to be
sib-divided into minute-enough particles to be suspended prolonguedly in the
approximately 'still'
Air, is all in the same Ball Park as 'Silica' related 'dusts'...as far as
'concern' for subsequent Lung problems are concerned, if these dusts are
aspirated and are not soluble to the chemistry if the Lung's ability to
dissolve them, or, expel them by floating them out on mucous.
That's my recollection or acceptance, anyway...
Observe one's own livingroom in occasions of a Sun 'fan' entering through a
window, and see the illuminated 'dusts' being held in the otherwise still
Air.
One breathes these routinely, constantly, in all indoor places of usual
decor
or kind, and, usually, they are not 'good' ( either), being decomposed
fragments of synthetic 'fibres' of the carpet, drapes, clothing or whatever
else, Mold spores, Nematode 'husks' and assorted else...along with whatever
approximately soluble 'Organics'.
Anyway...
Just a couple thoughts on all that...
Love,
Phil
l v
----- Original Message -----
From: "Ron Roy"
> Hi Jon,
>
> Desert sand is rounded so they get a different kind of effect - I think I
> remember - not so dangerous.
>
> RR
>
>>I am no expert, but It was always explained to me that particle size
>>is what is important. the other materials can get breathed back out,
>>but that the silica particles get so small that they are trapped deep
>>in the alveoli, and stay put. It was only recently that I had heard
>>the the silica particles actually cut and scar your lungs. My
>>understanding of asbestos, was that it has little hooks that catch on
>>your lung tissue and that the lung tissue scars and also envelopes it.
>>
>>is there a doctor in the house?
>>
>>if silica is so bad, (which I believe that it is) do people who live
>>in sandy deserts such as the middle east have higher incidences of
>>silicosis?
>>
>>jon
>
> Ron Roy
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