Bill Edwards on sat 3 jan 04
Ron made a good point that I would add to. Why would
we want to inhale any of the burned off compounds
since all would be toxic to some degree no matter what
it is? Chrome 3 is no worse than cobalt or copper if
we are subceptable to having any degree of reaction
from either of these materials based on the
individual.
All potters need to know that vapors from a kiln carry
with it risks if they are staying around long enough
to smell the fumes. Venting is good, continued
cleaning in the studio is also good! Wear a mask,
don't stir up dusts and simply keep a good clean
studio and if you cant leave the area when firing then
know that many of our products will fume that are just
as toxic as burning plastic in a sealed in room. Tin
of course will always remain one of the chrome tin
pinkers (When chrome is present) based on the chemical
reactions of volatile compounds during burn off
altering the tin whites can reduce this as well to a
point where this pinking doesn't happen. It happens or
can happen in rutile as well in some glazes. Ask
yourself if the tin white is acidic or alkyline first.
Check your flux(s). See where your AL:Si Ratio is at
and look at the boron content. Reduce the tin some if
you still have this problem and replace some of it
with another opacifier contain zirconium or whatever
else you may choose if the recipe is so good that you
wouldnt want to change it with glaze calculations. Ron
might even have a white that would contain tin and not
pink that he could offer out here? Or is he saving
this for the next book? Inquiring minds want to know.
I love FAT tin whites and chrome anyways and can
always use another FAT white that won't pink unless I
want it to. What I find is this, Copper can be a
hazard to those with Wilsons disease. I can't find
anyone that has a similar problem with Chrome 3
compounds or a disease triggered by it use. But yet we
indulge right along in the copper recipes without all
the haggleing back an forth. Humans hang on to copper
like they do lead as we grow thus increasing this
potential. Then of course I still see people all the
time cooking on TV using copper pots. A chrome tin
red recipe calls for less that one half of a percent
0.5% by weight. Then we use 2+% give or take with many
other coloring oxides. If we used 2% of chrome in a
glaze thats usually over-kill since its about as
strong a colorant as cobalt in some ways. There are
some people who can't handle iron. Copper will flux
and help melt a glaze to the point of running off a
pot. Thats pretty powerful! Wrap a copper wire around
a pot sometimes and see whats left. This is all pretty
normal with most metal oxides. Some are more visually
appealing and excites the eyes more so than others.
Turquoise is achieved by a tin copper reaction in the
^6 oxidation atmosphere. A glaze containing a strong
sodium combined with tin and copper usually can
produce this change. Now how do we entice copper to
emit to a blue hue, is it alkyline or acid or does it
matter? These things happen in firing and its a lovely
thing. (I am aware of the ? statement, just wanted to
add this to help some others think on it a little) Tin
seems to play a large part in getting reds in redux.
Lots of good things happen in various firings that
help us make pots that are entertaining and
enlightening and I still think all can be dangerous or
all can categorized based on known factors that have
at least been time tested. Lead, Barium, Lithium,
Cadmium have long histories they carry known risks
based on historical studies and toxicology. Try
Erbium, praseodymium, neodymium and try using these to
make macro-crystaline glazes. Not known to be a risky
colorant and WOW, I have only seen a few samples of
these but there are beauties. These materials have
been around a long time and now are just seeing the
light of day in pottery. They are supposed to be in a
low order acute or chronic toxicity based on available
information maybe we can eventually produce using less
and less problematic materials. I have experimented
lightly with a few of these (non crystal) and they
have a picky nature but they work. they have few risks
that are known but I still wouldn't recommend standing
around the kiln because its not just the colorants
that are losing knoxious gases that are toxic.
http://www.wilsonsdisease.org/about%20wilsons%20disease.html
Common sense and good basic knowledge is a powerful
tool and goes well with good calculations and testing
which will lead to more improved product and health as
time goes by. So it is all good and yet ever tiring to
keep pace with the changes. Its still a worthwhile
health investment to learn as much as possible if you
intend on handling these compounds over the years and
putting them to use in your personal space. Then it
does make good sense not to stick around and smell the
wonders that are cooking in the kiln, after all, its
not chicken in there frying... or is it?
Its unfortunate how many public studios I know that
throw anything they can in a mix and just hope for the
best with little use or knowledge of chemistry or even
how to read the MSDS and product information sheets
even if they have one on hand. I am not speaking of
personal studios, just places that offer to teach
pottery but have little means of knowing the
difference between the good, the bad and the ugly.
(Seen this happen once too often) They just assume
control over the position and take off as if they
worked for it all their lives. Some are good at what
they do and some really suck at it. Once again thats
why I advocate Clayart so strongly, its a wonderful
teaching tool (Maybe some of these places I speak of
will learn from this group) and anyone who leaves here
because it gets a little heated up on occasion are
missing out on great educational opportunties that
won't be found easily anywhere else. If someone throws
in a bone about their grandchildren or soy milk they
have most likely earned enough points to do so and
have contributed enough to warrant this on occasion in
my most humble of opinions. But then a couple of my
posts have came up missing so maybe I am irratating
the judges on occasion or the space monster decided to
eat them. It does take energy to produce these posts
so maybe saving them and re-sending them over and over
will be the best method for quality/quanity control on
my part.
Bill Edwards
Ron stated -
There have been many reports of tin glazes turning
pink over the years -
many right here on clayart - there is no doubt that
chrome is volatile -
the questions are - how much do we need to inhale
before it's a problem and
what is our personal susceptibility.
RR
=====
http://www.geocities.com/tallapoosarivergallery/index.html (Coming soon)
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"Anyone whose panties get in a bunch over what I have to say from my
tiny corner oughta order some bigger roomier panties....!" A candle for Arti
Bill Edwards
PO Box 367
Camp Hill, Alabama. 36850
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