Kate Smith on wed 13 jan 99
I bought a sample of ash from a local supplier for a trial. Glaze worked
well. I asked for a copy of lab analysis and found it contained 1 ppm of
lead/Pb.
I did the over the counter Lead test. The result was acceptable in that
it was negative. I am hesitant to use this ash again.
Am I right in assuming the lead may build up within the kiln. Over time
this accumulation to contaminate load upon load of glazeware?
Phil Smith
Phil & Kate Smith
PotterSmiths'
White Bear Lake, MN
Paul Lewing on thu 14 jan 99
Kate Smith wrote:
>
> ----------------------------Original message----------------------------
> I bought a sample of ash from a local supplier for a trial. Glaze worked
> well. I asked for a copy of lab analysis and found it contained 1 ppm of
> lead/Pb.
>
> I did the over the counter Lead test. The result was acceptable in that
> it was negative. I am hesitant to use this ash again.
>
> Am I right in assuming the lead may build up within the kiln. Over time
> this accumulation to contaminate load upon load of glazeware?
This is truly paranoid! The ash contains 1 part per million lead! If
the glaze is even one half ash, the whole glaze contains 1/2 of one
part per million lead. Now think about how much weight of glaze there
is in a firing. Maybe 500 grams? That's .0005 grams of lead total!
That's 5 ten-thousandths of a gram! And very little of that will
volatilize, and even less of that amount will stay on your kiln walls,
and even less of THAT will revolatilize, and even less of THAT will
deposit on other pots! If you've ever even WATCHED someone smoke a
single cigarette, you've gotten more lead into your body than someone
could possibly get from using pots fired in this kiln.
Sorry, Kate and Dale, I didn't mean to unload on you, but often on
this list I see people ask questions about the toxicity of materials
that, if they only did a little math, they could see were silly. Yes,
some of these materials are toxic, but we need to think about how they
are toxic and when. If this kind of thinking becomes prevalent in the
public, imagine the reaction. "Oh my God, some glaze materials that
those hand potters use contain up to 1 PART PER MILLION LEAD!!!! We'd
better buy plastic!"
I'll stop ranting now and go away.
Paul Lewing, Seattle
Lee Love on sat 16 jan 99
I wasn't able to read all the messages in this string so I don't know if
this question has been answered. Here is what I have for Mt. St.
Helen's volcanic ash:
Ca0 6.81%
Mg0 6.11
K20 .5
Na20 3.9
Fe203 6.81
Mn0 .2
Ti02 .3
P205 .2
Al203 22.32
Si02 51.85
/(o\' Lee In Saint Paul, Minnesota USA 0
\o)/' mailto:Ikiru@Kami.com ICQ# 20586182
' http://www.millcomm.com/~leelove/ikiru.html
Michael McDowell on sun 17 jan 99
Lee Love wrote in asking for feedback on his analysis for Mt. St. Helens
Volcanic Ash. Lee I have 9 different analyses in front of me right now that
were done on samples taken from various places both near and far from the
source volcano. These analyses were done by a fellow named G. Mustoe just a
month after the eruption in 1980. I got them from a professor in the Geology
Dept. at the local University. From looking at these figures it appears that
there was some pattern to their variation. For deposits at great distance from
the volcano, such as Spokane, Denver, and Missoula the percentage of Fe2O3
tends to drop off from close to 7% to more like 4.5%. Alumina is highest near
the volcano, but never more than 19.69%, dropping off to 16.5% at the most
distant sites. None of the analyses I have show Calcia above 6.05. I also have
higher percentages all round on K2O and Na2O than you present. I'm not saying
my numbers are better just because there are more of them. I'd be interested
to know more about the source of yours. Below I'm including a table (hope the
formatting holds) showing the difference between your analysis and the one for
ash collected near Spokane. I use this one because its the site closest to
Ritzville, where I got mine.
Oxide........Lee's #'s.............My #'s
Ca0...........6.81%...................4.19%
Mg0..........6.11......................1.78
K20 ..........0.5.......................1.65
Na20.........3.9.......................4.59
Fe203.......6.81......................4.19
Mn0..........0.2........................0.07
Ti02..........0.3........................0.52
P205........0.2........................(trace)
Al203.....22.32......................18.46
Si02........51.85......................66.05
Michael McDowell
Whatcom County, WA USA
mmpots@memes.com
http://www2.memes.com/mmpots
Jon Pettyjohn on tue 19 jan 99
Hi,
Couldn't resist making a quick comparison of the
Mt. St Helen's ash analysis from Lee Love and an
analysis of Mt. Pinatubo's made shortly after the
eruption. Although not the same they would seem to
be similar materials in spite of being an ocean
apart.
St. Helen's Pinatubo
Ca0 6.81% 5.66%
Mg0 6.11 2.75
K20 .5 1.66
Na20 3.9 4.48
Fe203 6.81 5.66
Mn0 .2
Ti02 .3 .84
P205 .2
Al203 22.32 16.19
Si02 51.85 61.90
Thanks to Joseph Herbert for reposting his article on
volcanic materials. From his info it would seem
the ashes from these 2 volcanoes are both of the high
silica, explosive type as I guess are all the Pacific
rim volcanoes. Would that be right? The Pinatubo ash
makes a good glaze (brown slightly metallic) on it's
own at ^9-10.
It would be interesting to put together a little chart
of various ash types for comparison, I know that some
other analysis were posted recently too but I for one
would like to see more if anyone else has some.
BTW when it comes to comparing raw materials I think
I'm more comfortable with percent than Seger ratios, I'm
not sure why, I wonder if anyone else would agree.
Jon Pettyjohn
jon@mozcom,com
Laguna, Philippines
From the foot of Mt. Makiling, yet another dormant volcano,
hoping it stays that way.
Martin Howard on tue 19 jan 99
Jon Pettyjohn says:-
It would be interesting to put together a little chart
of various ash types for comparison, I know that some
other analysis were posted recently too but I for one
would like to see more if anyone else has some.
I posted a little earlier about different Granites used by monumental
masons, and about montmorrilinite etc. Some of these things are in the
large books, but the information seems to be rather scattered.
There is also the problem that we are all working at different cones.
But why do I seem to be the only one working at 02-1? Is there some
problem that I have not yet found at those temperatures, other than an
absence of glaze recipes not based on lead or fritted lead?
Martin Howard
Webbs Cottage Pottery and Press
Woolpits Road, Great Saling
BRAINTREE
Essex CM7 5DZ
01371 850 423
araneajo@gn.apc.org
=?iso-8859-1?Q?Ren=E9?= Sprattling on thu 4 feb 99
>----------------------------Original message----------------------------
>I bought a sample of ash from a local supplier for a trial. Glaze worked
>well. I asked for a copy of lab analysis and found it contained 1 ppm of
>lead/Pb.
>
>I did the over the counter Lead test. The result was acceptable in that
>it was negative. I am hesitant to use this ash again.
>
>Am I right in assuming the lead may build up within the kiln. Over time
>this accumulation to contaminate load upon load of glazeware?
>
>Phil Smith
>
>Phil & Kate Smith
>PotterSmiths'
>White Bear Lake, MN
What cone are you firing to? It is my understanding that lead burns out at
temps over 1800F. If you are firing above bisque temperatures you should
not have any problems.
Rene
Stone Burner Studio
Muddy
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