Joyce Lee, Jim Lee on fri 15 nov 96
I just had a disastrous reduction firing. Three glazes ran badly
over my shelves(acutally they "ran" very well). One was a rutile blue
glaze that I think I probably didn't concoct correctly. The second,
though, is a clear commercial glaze I have used several times. The
third is a commercial celadon with which I, also, have had experience.
However, this is the first firing where I have achieved cone 10, with
the cone 10 cone laying flat on the shelf. I seem to have two
questions: (1) Have I given you enough information for you to make a
guess as to what happened (2) How do you get those puddles of glaze off
your shelves? Chisel and hammer? Some kind of grinder? Any response
would be appreciated.
Joyce
Back in Mojave instead of midway between low and high
Cathy Nelson Hartman on fri 15 nov 96
Dear Joyce,
Use a grinder with silicon carbide grinding disk. Use a mask. And cone 10
flat is at least cone 11 if not 12. "cone 10" usually refers to either
cone 10 at "three o'clock" or some say "with the tip just touching the
shelf". So you probably overfired the glazes.
Walter
Walter Hartman full time studio potter since 1973
cone 10 porcelain
90% functional work
Hartman Pottery oxidation in gas kiln
1600 Willowwood sell all work at art fairs
Denton, TX 76205 work by myself
(817) 382-1083
e-mail: cnh0002@jove.acs.unt.edu
Marcia Selsor & Matt Benacquista on fri 15 nov 96
Joyce Lee, Jim Lee wrote:
>
> ----------------------------Original message----------------------------
> I just had a disastrous reduction firing. Three glazes ran badly
blue ....How do you get those puddles of glaze off
> your shelves? Chisel and hammer? Some kind of grinder? Any response
> would be appreciated.
>
> Joyce
> Back in Mojave instead of midway between low and high
Yep. Chisel and hammer to start. WEAR EYE GOGGLES!!! Chips of
glaze can damage eyes. After chieling the bulk off the shelf, I use a
Makita pneumatic (compressed air) body grinder with a carbide disk
and grind down as far as I can without damaging the shelf. If you place
the shelf on a bag of clay, this cushions it. Some glazes can really eat
up shelves, like a raku glaze mistakenly placed with the stoneware
pieces by a student who hasn't grasped temperature differences.
Rewash the shelf and fire again. Best wishes.
Marcia in Montana (pretty good at safeguarding shelves on a very
stringent budget in Montana where teachers and education are at the
bottom of national spending)
--
Marci Selsor
Matt Benacquista
http://www.imt.net/~mjbmls/
mjbmls@imt.net
Dave and Pat Eitel on fri 15 nov 96
Joyce--Seems like you overfired. Did you use a guard cone--a ^11 or 12--to
let you know how high you actually went?
Later...Dave
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
pots@cedarcreekpottery.com
http://www.cedarcreekpottery.com
"Rafael Molina-Rodriguez (Rafael Molina-Rodriguez)" on fri 15 nov 96
Joyce :
If you are going to use fluid glazes (i.e. rutile blue, copper red, copper
purple, wood ash) my suggestion is to make a thin (1/8 ") pad of moist
clay and dip it into kiln wash (kaolin/alumina hydrate). Place a "pad"
under each object being loaded into the kiln. Make sure the pad extends
beyond the base of each object approximately 1/2 ". This will catch any
runoff glaze. The pads can be used repeatedly. I've fired some a dozen
times.
Glaze application is an important consideration. It's possible you applied
the glazes on too thick. Fluid glaze thickly applied on a vertical surface is
a bad situation. The problem with glaze application is you have to get the
glaze on thick enough to develop the correct color and texture. If too thin
it will not be the correct color or texture. If glaze is too thin you can run
your finger across the surface of the object and feel the texture of the
clay through the glaze.
You must be careful when cleaning glaze runoff on shelves. I place a
thick piece of foam under the shelf as I work on it. This acts as a shock
absorber. If you work directly on a hard surface you may break the
shelf. Begin with hammer and chisel. Wear safety goggles. After
hammer and chisel, use hand held masonry abrasive stone to grind
down larger pieces of glass. Finally, use hand-held power grinder to
take glass down to final surface.
Good luck!
Rafael
rmr3431@dcccd.edu
>>> "Joyce Lee, Jim Lee" 11/15/96 06:56am
>>>
----------------------------Original message----------------------------
I just had a disastrous reduction firing. Three glazes ran badly
over my shelves(acutally they "ran" very well). One was a rutile blue
glaze that I think I probably didn't concoct correctly. The second,
though, is a clear commercial glaze I have used several times. The
third is a commercial celadon with which I, also, have had experience.
However, this is the first firing where I have achieved cone 10, with
the cone 10 cone laying flat on the shelf. I seem to have two
questions: (1) Have I given you enough information for you to make a
guess as to what happened (2) How do you get those puddles of glaze
off
your shelves? Chisel and hammer? Some kind of grinder? Any
response
would be appreciated.
Joyce
Back in Mojave instead of midway between low and high
Vince Pitelka on tue 19 nov 96
Dear Clayart Friends -
I have not received any clayart for the last two days. Just started
receiving again today. This apparently happened to many people. At any
rate, I had sent this message several days ago and have no idea if it ever
got through. I did not receive that friendly confirmation from the list, so
I am assuming that this did not get through, and am reposting it.
>I just had a disastrous reduction firing. Three glazes ran badly
>over my shelves. . . . .
>How do you get those puddles of glaze off
>your shelves? Chisel and hammer? Some kind of grinder?
>Joyce
Joyce -
Without knowing more about your glazes it is hard to say why they ran so
badly. Some high-gloss ^9-10 glazes become quite runny at a flat ^10,
especially if applied a little heavily.
Regarding cleaning shelves, the technique which you can most effectively use
depends on how well the shelves were coated with kiln wash. If you had a
good thick layer of kiln wash then the glaze should chip off fairly easily
with proper use of a hammer and chisel. Proper use implies a smallish
hammer, a chisel sharpened to a skew-wedge tip (where one sharpened face is
almost parallel to the shaft of the chisel, while the other is at
approximately a 45 degree angle to the shaft). Place the shelf on a soft
surface, like a flat piece of foam rubber, a stack of rags, or a bag of
sand, so that it is fully supported under the ENTIRE shelf. Use the chisel
with the flat side against the shelf and the angled side facing upwards, and
chisel sideways parallel to the shelf against the glaze accumulations.
NEVER chisel straight down against the shelf. If the glaze runs are not too
badly melted to the shelf you should be able to chip them off by this method.
If the runs are very badly melted to the surface of the shelf you will have
to grind them off. Purchase or borrow an angle-head grinder, like a Makita,
Milwaukee, Ryobi, Skill, etc., and purchase a 4" cup stone with an
appropriate thread to fit the grinder. Most angle-head grinders have a
standardized threaded shaft (5/8" by 11 threads per inch), so you will have
no trouble getting the right stone. This kind of grinder is very handy for
many purposes, and any serious potter should have one. The angle-head
grinders come in two sizes. The smaller size is adequate for most
applications, is much easier to handle, and is much less expensive. You
should be able to get a good one for less than $100.00. The cup stone is
available at any good welding supply or mill supply.
Whether you grind or chisel the shelf, make sure it is evenly and firmly
supported as described above. And always wear appropriate eye protection
and dust mask.
- Vince
Vince Pitelka - vpitelka@Dekalb.Net
Phone - home 615/597-5376, work 615/597-6801
Appalachian Center for Crafts, Smithville TN 37166
Terrance Lazaroff on tue 19 nov 96
Joyce:
You have answered all your questions. You probably over fired your glazes.
As the temp rises the glaze becomes fluid. As any fluid will, It will run.
In your case it was on to your kiln shelves. I hope you have used kiln wash
on your shelves. If you have than it should be easy to chip off the glass
with a hammer and chisel. BE SURE TO WEAR SAFETY GOGLES and to GRIND THE
SHELVE WITH A SOAP, afterwards to ENSURE NO FINE GLASS PARTICLES are
adhering to the shelves. These make nasty cuts. If you have not used kiln
wash the same procedure will be required. You will have to chip away the
glaze. This will mean loosing some of your kiln shef. You may even break
the shelve when you chip away at the glaze. Be careful. I suggest filling
the holes with grog and kiln wash because some glazes sink into the shef only
to come out during firing.
Advise. Be careful when mixing and firing your glazes. Keep notes. When
in doubt place the piece on a seperate tile.
Best regards
Terrance F Lazaroff
St Hubert, Quebec, Canada !!!!
Don Jung on tue 19 nov 96
Joyce Lee, Jim Lee wrote:
>
> ----------------------------Original message----------------------------
> I just had a disastrous reduction firing. Three glazes ran badly
> over my shelves(acutally they "ran" very well). One was a rutile blue
....snip........
> questions: (1) Have I given you enough information for you to make a
> guess as to what happened (2) How do you get those puddles of glaze off
> your shelves? Chisel and hammer? Some kind of grinder? Any response
> would be appreciated.
>
Someone else could probably guess better than I about the running (my 2
bits is that it's overfired).
I've had the unfortunately experience of taking off lots of glaze stuck
on a shelf though...
A carbide tipped or better yet, special diamond grit blade on an angle
grinder can do the job. You have to be very careful that you don't take
too much of the shelf out since the glaze will provide a lot of
resistance while grinding and then when it's all gone, you'll go right
through the shelf if you're not careful.
I would recommend you try the angle grinder if the mallet and chisel
can't do the job. Don't forget the goggles, mask, gloves, etc.
I'm looking around for a grinder that can do a 'flat' surface cut unlike
the angle grinder that uses the tip and cuts into the surface.
Hopefully though, I'll not need to use it.
Don
Talbott on wed 20 nov 96
>This is the second time that I have sent this msg....what is going on with
>the server????
I use a Milwalkee 6" body grinder with a wire brush cup attachment--I of
course dawn on the essential safety gear-- which includes safety goggles,
hearing protection, and dusk mask--this does the job for me --my shelves
are fairly hard since they are nitride bonded silicon carbide and I use
Lee's Incredible Kiln Wash from Axner which I swear by when I recoat my
shelves--when I first heard of the stuff I thought it was a rip off until I
lost a few $100 platters due to flaking kiln wash that got caught up in the
glaze--then I said what the "heck" and I tried it--I won't use anything
else now for kiln wash- Best-- Marshall
----------------------------Original message----------------------------
>I just had a disastrous reduction firing. Three glazes ran badly
>over my shelves(acutally they "ran" very well). One was a rutile blue
>glaze that I think I probably didn't concoct correctly. The second,
>though, is a clear commercial glaze I have used several times. The
>third is a commercial celadon with which I, also, have had experience.
>However, this is the first firing where I have achieved cone 10, with
>the cone 10 cone laying flat on the shelf. I seem to have two
>questions: (1) Have I given you enough information for you to make a
>guess as to what happened (2) How do you get those puddles of glaze off
>your shelves? Chisel and hammer? Some kind of grinder? Any response
>would be appreciated.
>
>Joyce
>Back in Mojave instead of midway between low and high
Marshall Talbott
Pottery By Celia
Route 114
P.O. Box 4116
Naples, Maine 04055-4116
(207)693-6100 voice and fax
clupus@ime.net
Jonathan Kaplan on wed 20 nov 96
OK, I'll tell you how I do it. I have alcorit shelves for the gas kiln and
loads of Thorley shelves as well as shelves from a Mexican refractories
company. I have never washed any of these shelves. In fact, my alcorit
shelves are well into the end of their second decade of hard use. Even
student work is fired on unwashed shelves.
Our maintenance for shelves in the plant is easy .Un load the kiln, scrape
the wadding off the bottoms of the shelves with a large flat masons chisel,
and use a silicon carbide masonary grinding brick (the one with the wooden
handle) to clean any and everything from the firing surface. Check
theshelves for warpage, and turn them over in the next firing.
We take the car down about every month and flip the shelves over and reset
the piers.
If the shelves are full o'crud, I use the sandblaster very lightly and it
removes even the most offending crud.
I'm a strong believer in maintaining both equipment and whatever associated
supplies are needed on a regular schedule. They last longer that way.
Jonathan
Jonathan Kaplan
Ceramic Design Group Ltd./Production Services
PO Box 775112
Steamboat Springs CO 80477
jonathan@csn.net
(970) 879-9139*voice and fax
http://www.craftweb.com/org/jkaplan/cdg.shtml
Kenneth D. Westfall on wed 20 nov 96
>Date: Fri, 15 Nov 1996 18:01:00
>To: Ceramic Arts Discussion List
>From: "Kenneth D. Westfall"
>Subject: Re: Cleaning Shelves
>
>At 12:56 PM 11/15/96 +0000, you wrote:
>>----------------------------Original message----------------------------
>>I just had a disastrous reduction firing. Three glazes ran badly
>>over my shelves(acutally they "ran" very well). One was a rutile blue
>>glaze that I think I probably didn't concoct correctly. The second,
>>though, is a clear commercial glaze I have used several times. The
>>third is a commercial celadon with which I, also, have had experience.
>>However, this is the first firing where I have achieved cone 10, with
>>the cone 10 cone laying flat on the shelf. I seem to have two
>>questions: (1) Have I given you enough information for you to make a
>>guess as to what happened (2) How do you get those puddles of glaze off
>>your shelves? Chisel and hammer? Some kind of grinder? Any response
>>would be appreciated.
>>
>>Joyce
>>Back in Mojave instead of midway between low and high
>
>I also have had such a dissaster and the best method I have found it a 4"
mini right angle grinder. I get the grinding wheels for concreat, they are
made out of silicon carbide instead of alumina oxide and seem to do a better
job. After grouding the glaze down flush you will want to cover the self
with liberal amount of kiln wash. It seem that glaze can bubbles up out of
the self pores and the wash will help stop it from damaging pot in the next
load. Ash glazes are the worst and need to be ground down several time to
get ridd of all of it. I have sometimes fire the selfs with nothing on them
for two or three loads to get ridd of all the glaze that purcalate up.
After each firing I will grind off the wash and any more glaze that come up
and them rewash. I take the old wash off so that it doesn't build up thick
and start flaking off. Happy Grinding
>Kenneth
>
DON'T GET STUCK IN THE MUDPIES--K & T
"Rafael Molina-Rodriguez (Rafael Molina-Rodriguez Rafael on wed 20 nov 96
Joyce :
If you are going to use fluid glazes (i.e. rutile blue, copper red, copper
purple, wood ash) my suggestion is to make a thin (1/8 ") pad of moist
clay and dip it into kiln wash (kaolin/alumina hydrate). Place a "pad"
under each object being loaded into the kiln. Make sure the pad extends
beyond the base of each object approximately 1/2 ". This will catch any
runoff glaze. The pads can be used repeatedly. I've fired some a dozen
times.
Glaze application is an important consideration. It's possible you applied
the glazes on too thick. Fluid glaze thickly applied on a vertical surface is
a bad situation. The problem with glaze application is you have to get the
glaze on thick enough to develop the correct color and texture. If too thin
it will not be the correct color or texture. If glaze is too thin you can run
your finger across the surface of the object and feel the texture of the
clay through the glaze.
You must be careful when cleaning glaze runoff on shelves. I place a
thick piece of foam under the shelf as I work on it. This acts as a shock
absorber. If you work directly on a hard surface you may break the
shelf. Begin with hammer and chisel. Wear safety goggles. After
hammer and chisel, use hand held masonry abrasive stone to grind
down larger pieces of glass. Finally, use hand-held power grinder to
take glass down to final surface.
Good luck!
Rafael
rmr3431@dcccd.edu
>>> "Joyce Lee, Jim Lee" 11/15/96 06:56am
>>>
----------------------------Original message----------------------------
I just had a disastrous reduction firing. Three glazes ran badly
over my shelves(acutally they "ran" very well). One was a rutile blue
glaze that I think I probably didn't concoct correctly. The second,
though, is a clear commercial glaze I have used several times. The
third is a commercial celadon with which I, also, have had experience.
However, this is the first firing where I have achieved cone 10, with
the cone 10 cone laying flat on the shelf. I seem to have two
questions: (1) Have I given you enough information for you to make a
guess as to what happened (2) How do you get those puddles of glaze
off
your shelves? Chisel and hammer? Some kind of grinder? Any
response
would be appreciated.
Joyce
Back in Mojave instead of midway between low and high
William Amsterlaw on wed 20 nov 96
Hi Clayart:
On 19 Nov 1996, Vince Pitelka wrote:
>>
If the runs are very badly melted to the surface of the shelf you will have to
grind them off. Purchase or borrow an angle-head grinder, like a Makita,
Milwaukee, Ryobi, Skill, etc., and purchase a 4" cup stone with an appropriate
thread to fit the grinder. Most angle-head grinders have a standardized
threaded shaft (5/8" by 11 threads per inch), so you will have no trouble
getting the right stone. This kind of grinder is very handy for many
purposes, and any serious potter should have one.
<<
Nine months ago I seriously injured my left hand while using a rag to wipe
glaze off the shaft of a Jiffy Mixer. The mixer was attached to a half-inch
hand-held drill. I had the mixer in a bucket of water and while it turned, I
ran a rag down the shaft. Years of working on a potter's wheel had accustomed
me to running my hands over spinning wet objects turned by powerful electric
motors. I had safely done the same thing many times, always careful to stay
well away from the spinning blades. In retrospect, what I was doing seems
pretty stupid, but never realized how powerful a half-inch drill really is
until I tangled with one (literally). The injury occurred when the rag got
tangled in the blades of the mixer ... and the rag instantly tightened up and
grabbed the end of my left index finger and pulled it off.
I tell this story to illustrate the fact that the power tools that we use can
cause serious injury. We could probably generate a huge list of dangers posed
by the improper use of these tools. I know something about workplace
dangers not just because I have been a victim. I also worked in a busy
emergency department for over 10 years.
Regarding the angle-head grinders.... I agree with Vince that it is an
incredibly useful tool. I have had one of these for over 10 years and have
used it thousands of times (without an injury). But I know this tool can be
dangerous and I want to make sure that others use it properly. The typical
angle-head grinder takes a 4" wheel and rotates at 10,000 rpms. Anything
flying off the wheel will be traveling at over 200 miles per hour.
1. Make sure that the "stone" you attach to the grinder is rated for at least
10,000 rpm's. Make sure the stone is undamaged. If you don't use a grinding
disk rated for at least 10,000 rpms which is in good condition, the disk can
be torn apart by centrifugal force.
2. Always wear eye protection. The danger to the eyes posed by any 200 mph
projectile is obvious. If you grind steel, those sparks that seem so harmless
to your skin can cause serious injury if one of them hits you in the eye. A
tiny piece of molten steel flying at 200 mph can imbed itself in your cornea
and will have to be surgically removed.
3. Wear a dust mask. If possible, do your grinding outdoors or in a
spraybooth. High-speed grinding will fill the air with microscopic glaze
particles.
- Bill Amsterlaw (wamster@msn.com)
Plattsburgh, NY
Don Jung on fri 22 nov 96
Jonathan Kaplan wrote:
>
> ----------------------------Original message----------------------------
> OK, I'll tell you how I do it. I have alcorit shelves for the gas kiln and ..
> handle) to clean any and everything from the firing surface. Check
> theshelves for warpage, and turn them over in the next firing.
>
I'm curious Jonathan, doesn't any glaze drip 'out' of a shelf that's
been turned over? I've come to believe that glaze drips can work their
way into a shelf and that even grinding doesn't remove it all...so when
a shelf is turned over and fired, the glaze drips work their way back
out and onto the pieces below. Does this happen to you at all?
thx
Don Jung
Kensington Pottery
Vancouver BC Canada
dojun@axionet.com
ph 873-1836 / 661-6723
Lily Krakowski on sat 15 mar 03
Vince's wonderful description of the ideal chisel for cleaning shelves
describes mine perfectly. It is, however, a very old woodworker's chisel,
almost the thickness of my pinkie, about 1.5 inches wide. I think it is
called a framing chisel? And of course it already only beveled on one side.
The previous owner had broken off or cut off the wooden handle, so only the
metal cup in which the handle sat is left. (and the wood stuck in it) This
was bought for a few dollars at some rural junk yard/ auction barn/ who
knows, and is a good thing to go look for....I prefer a chisel to a
grinder--much more control I think.
Kiln wash is like an apron. Period. It will not protect from Overhelming
Disasters (the puppy trips you as you are carring two gallons of borsch to
the fridge) but will protect from the smaller disasters: brownie dough
splashes, gravy drips, egg splatters. Ditto idea with shelves.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
BRIAN GUFFEY on sun 16 mar 03
In the studio i do ceramics in (and being the studio assistant) we use an=
angle grinder ... and boy does it do the job. it eats the spills from b=
egining students accidents with the glazing process like it is a play of=
ribs at an all you can eat contest.
Brian Guffey
----- Original Message ----
From: Lily Krakowski
Sent: Saturday, March 15, 2003 10:03 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: cleaning shelves
Vince's wonderful description of the ideal chisel for cleaning shelves
describes mine perfectly. It is, however, a very old woodworker's chisel=
,
almost the thickness of my pinkie, about 1.5 inches wide. I think it is
called a framing chisel? And of course it already only beveled on one si=
de.
The previous owner had broken off or cut off the wooden handle, so only t=
he
metal cup in which the handle sat is left. (and the wood stuck in it) Th=
is
was bought for a few dollars at some rural junk yard/ auction barn/ who
knows, and is a good thing to go look for....I prefer a chisel to a
grinder--much more control I think.
Kiln wash is like an apron. Period. It will not protect from Overhelmin=
g
Disasters (the puppy trips you as you are carring two gallons of borsch =
to
the fridge) but will protect from the smaller disasters: brownie dough
splashes, gravy drips, egg splatters. Ditto idea with shelves.
Lili Krakowski
P.O. Box #1
Constableville, N.Y.
(315) 942-5916/ 397-2389
Be of good courage....
_________________________________________________________________________=
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You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at melpots@pclin=
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