will edwards on tue 20 mar 01
Prior to reading this decide if you are interested in the above subject
line. DELETE if not. (Yes, it a long one)
Hello,
This post is a tad scientific but might be read by those interested in
glaze safety and making analytical observations for compliance with food
service glazes. Food service management and chemical formulation are the
major source of my education. I finished school at McKenzie college and w=
ent
on to develop a career in marketing art materials. (Several additional
certifications)I am still dumb as cold metal however! I am not a toxicolo=
gist
but many ask me questions which I am very familiar with. (over 20 years
research and hyper-anxiety for information). I suggest that when we post =
we
conclude only after we have either had tests ran or have seen the other s=
ides
of the issue via people like Edouard Basterache or someone who has a
back-ground for this information and education. Everyday I read posts in
regards to safety in the use of glazes. (It depends on many aspects) 1. T=
he
mixer. 2. The end user. 3. The ability to know heat work and glaze compos=
ition
and the resulting finish. (And then of course all the tests) Much can be
determined if they should qualify for lab testing by the calculations we =
make
if our imput information is good. But it is not fool-proof and is still b=
eing
studied by me and many others I am sure. we will never be able to make
toxicological evaluations using glaze chemistry calculations. (Observatio=
ns
and potentials are our tools without lab work).
Metals in water - They are several methods for determining this. (atomic
spectroscopy techniques and they all have different detection limits, lin=
ear
dynamic working ranges). or (ICP method). Vinegar is suggested by many at=
home
technical people. That will only be good for real bad glaze
concoctions in my opinion. Try some lemonaide as well. (Worthy of a firs=
t
round test) I made a 4% copper glaze that did not under-go any noticable
change with a 3 day soak in 5% acidic vinegar but still failed the tests.=
(I
looked under magnification) However the tests I used was stringent. I
purposefully used this to have a placebo for outside testing purposes. It=
is a
pretty glaze and will hold copper in a lower range. Add rutile or another=
item
and you might get more to stay in. It is based on the ability to find key=
s to
compositions that work in unity that helps decide hardness/softness. Add =
zinc
and it might get worse? Combined oxides can make a difference. That has
already been proven to me by my own lab results from an outside lab. (As =
if I
didn't suspect this anyways)
USDA, the USFDA and the USEPA are (Certifying authorities.) Also make cer=
tain
the lab is FDA/FSIS approved (See above) or meets compliance with the tes=
ting
procedures. If not then you are utilizing the information for
research only. ASTM (American Standards for Testing Materials) and the us=
e
of lab reporting will eventually lead us to master our efforts. (My book
might even help?) Below is a list for every possible lab you can think of=
=2E
Check it out!
http://www.astm.org/labs/NEW/filtrexx40.cgi?-P+SUBJECT+CH+subject.frm
Zinc intake with the addition of copper can make a very significant
difference than zinc alone. 60 mg/L of zinc can effect copper metabolism =
and
have serious effects. (FDA)
Copper currently is 1.3 mg/L or milligrams per liter or 1.3 parts per
million. This is called an action level based on a community or group whe=
re it
is considered a risk. wilson's disease is those who would be prone to adv=
erse
health effects of higher copper in any form. (MCLG's) Maximum contaminate=
level goals - are what much of these are based on and many are
non-enforceable. (Some do have action levels) What this does suggest is =
the
average person would live an average expected life time without any adver=
se
effect by staying within the (MCLG's). Copper is also essential for good
health and growth in regulated amounts. We need it to survive! So how man=
y of
us know exactly if we have too much or too little at any given time? Wils=
on
and Minkes disease are not included in this accessement.
Manganese - (secondry standards) meaning usually for taste, odor and clar=
ity
of water. 0.05 mg/L for manganese. Magnanese - Over-use or long term use=
include nervous system disorder. Sensitivity to this may occur in some pe=
ople
who have compromised immune systems. Not an accute toxin by
absorbtion through dermal contact and generally forms toxicity via fumes =
and
or inhaled micro-particulates over time. In digestion it is absorbed poor=
ly.
Another element we need in our systems. It is a major contributor to over=
-all
health. (How much is too much?)
Magnesium - Contributes to water hardness as well as calcium. An essentia=
l
element qickly removed from humans in good condition. Over-dose can produ=
ce
problems. These two are used to neutralize acid water thus making it more=
hard. (Works to improve blood pressure and low levels of magnesium have b=
een
found in people with CFS. Chronic Fatigue Syndrome) =
Nickle - 0.1 ppm. mg/L. Drinking water which meets the EPA standard is
associated with little to none of this risk and should be considered safe=
with respect to nickel.
Iron - (secondary standards) 0.3 mg/L. Essential for good health. I have
passed many tests with more than 10%+ of RIO. (Secondary means not regula=
ted
in this specific category) for testing. How many people take vitamins for=
iron
poor blood? How much is too much?
Lead - 0.015 mg/L. A no-no. The (MCLG's) for lead is zero. Lead is harmfu=
ll
and should not be used. Accumulative in the system. Get the lead out and =
keep
it out. (Any amount is too much!)
Chromium VI and III - VI (4) is associated with birth defects and cancer.=
III (3) is considered safe and is a low level micro-nutrient. Not known f=
or
bioaccumulation. The total levels for all chromium in domestic water supp=
ly
shows to be 0.05 mg/L. I also found 0.1 ppm for the same from EPA stats. =
(we
use it most everyday in some form.) It is known to help clean the arterie=
s and
works with insulin to metabolize sugars. Also helps transport amino acids=
within the system.
Cadmium - mutogenic potential (Genetic damage/mutation) Kidney disease an=
d
hypertension.
Barium - 1.0 mg/L High dosage can lead to heart problems, High blood
pressure and nervouse system damage. Strontium can replace this in some
glazes .75 to 1.00 ratio. The strontium I am talking about is the mineral=
not the isotope 90.
Aluminum - No criteria set that resulted in specific toxic reaction. One =
of
the earths most abundant metals. suspect only for nervous system issues.
Unkown and unproven. If it was an accute toxin perhaps all the cokes we d=
rink
that can eat away meat would have killed us already. (Silly humor) But it=
holds pretty well against coke in a can.
Calcium - In fish it has been known to reduce toxicity of certain other
levels of metals and other pollutants. Excessive over-use might contribut=
e
to calcification and develop into gall stones and kidney stones in humans=
=2E
The bodies way of ridding its self of too much of a good thing. We need u=
p
to 2.0 grams a day on average as a food element.
Fluorides - I don't care much for the use of added flourides myself. But
since it binds so well with metals it is noted that it will form compound=
s
with all elements except helium, argon and neon. It forms salts by combin=
ing
with metals.
Arsenic - It is wide-spread and needs no more spreading. Used in commeric=
al
processes and is becomming a health risk factor more and more. Arsenic is=
poison. Long term effects include loss of hair and weight, depression and=
nausea among other issues. I have heard it is a by-product of preserving =
wood.
Didn't check that one out!
I can't help but throw this in. When I see RO my mind thinks Reverse
Osmosis. I have to reconsider what we sometimes are talking about when it=
comes to calculations. I use 3 calculations methods myself and also a
toxicology data-base as well. So forgive my sometimes over-working a simp=
le
procedure. The above is a complilation of many documents and also lab rep=
orts
on my own materials or glazes. Nothing here is provided for any purpose o=
ther
than individual accessment for their own testing methods and procedures. =
The
FDA and USDA and a ton of other regulatory groups have much to offer on a=
ll
this. None of it is worth a plugged nickle with following up on the finis=
hed
glaze after firing to see what you can pull from it. Then and only then w=
ill
you know what is going on in your firing conditions. Variations in heat c=
an
make a difference also. QC is a hard girl to get and keep a date with. Or=
man.
(Pick one)
What all the above means is we have no positive way of knowing the exact
out-come of any material under varying operatives. We do know which ones =
are
not acceptable at any level. Then we have level (1) and level (2) or
secondary. Level one are known dangers or have risk associations. Level 2=
are
secondary and usually involve color, or taste problems and odors. The bes=
t
possible control over any of the issues is to consult with someone that y=
ou
trust about your glaze and then use the accessment to further the leverag=
e by
lab results. I can do this or provide you with ample information as I hav=
e
done in the above. Should a glaze need approval I can work the formulatio=
n out
as you write it and also have an approved lab to finish the results. Or y=
ou
can do it! Which ever rocks your world. But that is the only way we will =
ever
get the full story behind the mysteries of our work. Contact me off-list =
if
anyone needs further information! My few but long posts are only clogging=
up
the arteries of other great information here.
William Edwards
Alchemy 101 - My once a week to a month post. Yes, it is long! But it is
better than a million smaller ones is it not? Don't answer that...
____________________________________________________________________
Get free email and a permanent address at http://www.netaddress.com/?N=3D=
1
John Hesselberth on wed 21 mar 01
Hi Will,
I have interspersed some comments/questions below:
>
> Metals in water - They are several methods for determining this. (atomic
> spectroscopy techniques and they all have different detection limits, linear
> dynamic working ranges). or (ICP method). Vinegar is suggested by many at home
> technical people. That will only be good for real bad glaze
> concoctions in my opinion. Try some lemonaide as well. (Worthy of a first
> round test) I made a 4% copper glaze that did not under-go any noticable
> change with a 3 day soak in 5% acidic vinegar but still failed the tests.
What are your criteria for failure? There are no standards for any metals
leaching from ceramic vessels other than for lead and cadmium. Have you
made up your own? What data do you have to support them? I suspect from
your paragraphs below you are using drinking water standards. If so, could
you refer me to the data that says those are relevant?
I agree with you that passing the vinegar test should not be the end point
of testing; however if there is a color change in the vinegar test the glaze
is very unstable. The vinegar test is extremely useful in screening out
unsatisfactory glazes.
>
> Copper currently is 1.3 mg/L or milligrams per liter or 1.3 parts per
> million. This is called an action level based on a community or group where it
> is considered a risk. wilson's disease is those who would be prone to adverse
> health effects of higher copper in any form. (MCLG's) Maximum contaminate
> level goals - are what much of these are based on and many are
> non-enforceable. (Some do have action levels) What this does suggest is the
> average person would live an average expected life time without any adverse
> effect by staying within the (MCLG's). Copper is also essential for good
> health and growth in regulated amounts. We need it to survive! So how many of
> us know exactly if we have too much or too little at any given time? Wilson
> and Minkes disease are not included in this accessement.
>
> Manganese - (secondry standards) meaning usually for taste, odor and clarity
> of water. 0.05 mg/L for manganese. Magnanese - Over-use or long term use
> include nervous system disorder. Sensitivity to this may occur in some people
> who have compromised immune systems. Not an accute toxin by
> absorbtion through dermal contact and generally forms toxicity via fumes and
> or inhaled micro-particulates over time. In digestion it is absorbed poorly.
> Another element we need in our systems. It is a major contributor to over-all
> health. (How much is too much?)
>
> Magnesium - Contributes to water hardness as well as calcium. An essential
> element qickly removed from humans in good condition. Over-dose can produce
> problems. These two are used to neutralize acid water thus making it more
> hard. (Works to improve blood pressure and low levels of magnesium have been
> found in people with CFS. Chronic Fatigue Syndrome)
>
> Nickle - 0.1 ppm. mg/L. Drinking water which meets the EPA standard is
> associated with little to none of this risk and should be considered safe
> with respect to nickel.
>
> Iron - (secondary standards) 0.3 mg/L. Essential for good health. I have
> passed many tests with more than 10%+ of RIO. (Secondary means not regulated
> in this specific category) for testing. How many people take vitamins for iron
> poor blood? How much is too much?
>
> Lead - 0.015 mg/L. A no-no. The (MCLG's) for lead is zero. Lead is harmfull
> and should not be used. Accumulative in the system. Get the lead out and keep
> it out. (Any amount is too much!)
While I agree that studio potters should not be using lead based glazes
because we typically do not have the resources to be able to assure its safe
use, I do find lead a useful reference point. Lead and cadmium are the only
2 materials where there are standards for BOTH leaching from ceramic vessels
and for drinking water. It is interesting to note that the standards for
ceramic vessels are from 7-200 times higher (depending on the type of
vessel) than the standards for drinking water. This is presumably because
it is recognized that the leaching test using 4% acetic acid is far more
rigorous than is encountered in normal use. Indeed in a test I did a couple
years ago, normal use of a coffee cup results in leaching of only about 3%
of the leaching in the leaching test.
>
> Chromium VI and III - VI (4) is associated with birth defects and cancer.
> III (3) is considered safe and is a low level micro-nutrient. Not known for
> bioaccumulation. The total levels for all chromium in domestic water supply
> shows to be 0.05 mg/L. I also found 0.1 ppm for the same from EPA stats. (we
> use it most everyday in some form.) It is known to help clean the arteries and
> works with insulin to metabolize sugars. Also helps transport amino acids
> within the system.
>
> Cadmium - mutogenic potential (Genetic damage/mutation) Kidney disease and
> hypertension.
>
> Barium - 1.0 mg/L High dosage can lead to heart problems, High blood
> pressure and nervouse system damage. Strontium can replace this in some
> glazes .75 to 1.00 ratio. The strontium I am talking about is the mineral
> not the isotope 90.
>
> Aluminum - No criteria set that resulted in specific toxic reaction. One of
> the earths most abundant metals. suspect only for nervous system issues.
> Unkown and unproven. If it was an accute toxin perhaps all the cokes we drink
> that can eat away meat would have killed us already. (Silly humor) But it
> holds pretty well against coke in a can.
>
> Calcium - In fish it has been known to reduce toxicity of certain other
> levels of metals and other pollutants. Excessive over-use might contribute
> to calcification and develop into gall stones and kidney stones in humans.
> The bodies way of ridding its self of too much of a good thing. We need up
> to 2.0 grams a day on average as a food element.
>
> Fluorides - I don't care much for the use of added flourides myself. But
> since it binds so well with metals it is noted that it will form compounds
> with all elements except helium, argon and neon. It forms salts by combining
> with metals.
>
> Arsenic - It is wide-spread and needs no more spreading. Used in commerical
> processes and is becomming a health risk factor more and more. Arsenic is
> poison. Long term effects include loss of hair and weight, depression and
> nausea among other issues. I have heard it is a by-product of preserving wood.
> Didn't check that one out!
>
>
I am concerned that you are suggesting that, by default, we consider water
standards as something we impose on ceramic leach testing with 4% acetic
acid. While I consider water standards a useful reference and a
way-on-the-safe-side set of numbers, I have yet to see one shred of data
that says they would be appropriate standards. If that data exists, please
help me locate it.
While I share your concern that there are too many people putting poorly
made, unstable glazes on the market and that we should be learning how to
make our glazes as stable as possible, I personally reject the point of view
that we should try to arbitrarily impose standards where not a bit of data
exists to support the need for them. I am uneasy that that is what you are
warming up to.
Regards, John
Web site: http://www.frogpondpottery.com Email: john@frogpondpottery.com
"The life so short, the craft so long to learn." Chaucer's translation of
Hippocrates, 5th cent. B.C.
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