bill edwards on sat 23 apr 05
Vinegar is acidic. Acids attack surfaces that
otherwise would appear ok to the eye. It's not a
substitute for lab testing but more so a way to
understand if a glaze is simply not suitable for food
bearing surfaces. But....the end use may not be
intended for food, will it still be the right answer
for an artistic glaze?
What I believe our experts are trying for are several
things. One, they often make a living at what they do
and rightfully deserve payment for services rendered,
so not all information is given in full context. But
they do give out good advice where safety concerns
come into play more often than not. A potter makes
money from pottery, those with a chemistry background
and greater understanding should be given that same
arrangement and a great potter would be willing to
spend a little of their proceeds in learning and
higher eduation. With that said; our expert people
also give out often FREE advice which is great and
goes well beyond the norms of traditional information
that's simply found by accident because you have some
inter-action between parties. The movement is to get
more people involved in making safer pottery since so
much is used in food services and even if not, the
glaze should stand the test of time! Jonathans job is
to provide that kind of information and product to a
customer as is Ron and John and several others who
earn their fair share by studying and living with
science as a basis for their theory in pottery
chemistry. Some come with a fee, some don't. But a
minor investment for the long haul saves you money,
it's not like losing a load of pots or having several
bags of bad chemicals you can no longer use. It's a
wise investment in your future. Penny wise or pound
foolish?
If you make a load of bad pots and your customers
start complaining, you have lost much more than what
the initial costs would be for simple testing that
usually runs less than 50 dollars per glaze tested and
you don't need 500 glazes to have a nice selection.
For artistic art and basic understanding of food
wares, you can usually make a well formulated glaze
with some understanding of calculations tools or with
paper and pencil if you have some understanding of
principles applied through basic chemistry and make
glazes that might be used for flower pots or wares not
directly intended for food or with more experience
food wares as well that can be tested further through
labs. Now to close the argument a little more...
Bad glazes can leak, crawl, pit, craze or be
problematic in other ways. Some are made to do all the
above for esthetic purposes. But when you get the
above problems in areas you don't want them, it's time
for change. Lemon or vinegar is simply used to see if
any of the colorant oxides are coming from a fired
piece. If so, then other materials are riding in with
it. I noticed where someone said they had a piece with
a high iron glaze on it formulated a certain way and
that it has lasted forever. Good! Thats not the case
always, and its not a suitable answer for all cases
nor should it be. We have no way of measuring the
validity of the product, the method in which fired or
the exact materials used to make this glaze. Lab
testing would be the answer if a claim like that is to
be made public since any legal challenge in court
would need this information from a certified lab. A
jury might would understand some of the other methods
better but the bottom line is provable safety if you
are talking about service wares where a person could
be contaminated by some flawed product and if you
don't think people have gone law-suit crazy, think
real hard. And it doesn't matter if your wrong or
right! So we are back to square one again as we have
been over the years. Acidic testing is a visual
determination of potential problems, certified lab
extractions are more suitable for food wares, artistic
glazes are your choice if you use common sense
approaches where you know for a fact the end use could
not be used in any sense for storing food or cooking
from it. But wouldn't you still prefer a glaze that
would still be around long after the user? Thats the
next argument most guru's out there try to validate!!!
Durable use materials that can be replicated as often
as possible, when and where practicle. I, nor any
other person with reasonable experience would expect
perfection in all areas and some glazes reach well
outside known parameters science has set for various
reasons. What all of us want are simply better glazes
regardless. (Then of course those like myself would
easily say its probably not a great glaze and we would
talk about it and try to resolve some, if not all, of
it's problems provided the minimal information often
seen or gleemed from the knowledge base given at the
time) All this talk is nothing more than trying to
reach the highest level of intelligence in our field
in understanding the processes better. We want to make
artistic glazes that lasts longer, we expect to make
foodware glazes that are safe. But we must also make
sure that the manufacturer is put to the test as well
and that their materials are up to snuff and they too
are doing what we are paying them to do consistently.
If they don't, they lose money and customers and most
don't want to do that. Pick your materials wisely,
build a relationship with your suppliers. Learn which
materials offer consistency and realiability and do
those in-home tests to help you develop better glazes
or pottery and continue testing them till you think
you have a winner. If your making mistakes it's not
always the manufacturer's fault so who do you want to
blame? (no need in answering that) If you have that
one of a kind glaze that you need to put on service
ware, send a test sample out for extraction and don't
indulge your recipe to outside source other than the
lab who usually signs secrecy agreements. Thats where
you make your money, saves you butt, have one of a
kind art and earn respect from collectors who trust
you.
Bad Glazes: They are countless glazes that are
invented out there that many should or could share
here that are no big secret. The 'KEY' would be to
watch the arguments between the guru's and see how the
story un-folds to get a bad glaze to go good and still
have that same visual stimulation it had when it was
playing bad boy. This is not always going to work, so
the compromise is up to the potter now. What are you
willing to compromise with all this information or how
will you use it now?
Beginners - Please, always challenge yourselves and
never fear the sometimes short answers you get. Your
imput is as vital as the person who knows everything,
so they think! I admit my failures and actually enjoy
that aspect of being human. But I don't back down from
right against wrong and I relent when wrong, when
proven. It bothers me that I see too many new potters
say they have a fear of posting on our group because
they don't want their heads chewed off. Well chew back
a little, give some history and if some are willing to
moan and groan at you, it would surpize me they had
the energy for that but not enough energy to answer
you with dignity you all deserve. So stick in there,
don't sweat the small stuff and never let anyone stop
you from being the best potter you can be! And while
we all know about the archives we also know how things
change so gather your questions well and maybe someone
will answer them well with respect to the person who
asks. Things get better, glazes over the last 5 years
have vastly gotten better because of all this. And
yes, its all worth the argument to get to the root of
the problem and increase your knowledge base as often
as possible. It called learning! There's a few left in
our World who have learned it all. So let them have
their space and the beginners and mid-termers can
still keep poking holes in theories and exploring the
rest of the stuff and enjoying the friendships and
travels.
And while I wouldn't make or sell a ware made with the
floating red glaze as it stands, I would eat off it
myself and consider myself as getting an extra dose of
iron for the day, some people cannot handle additional
iron and its potentially a real problem for them.
Thats the difference in knowing. So I would make it
better and instead of eating off it, I might even cook
something in it or let it set in my fridge for a few
days with tomatoe soup in it!
Bill Edwards
Edmar Studio and Gallery
Subject: Re: Floating Red/Foodsafe? - vinegar test
What is the 3 day vinegar test?
Deborah J. Bassett-Maxwell
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