Earl Brunner on sun 20 sep 98
This past week there was a post about a glaze that someone felt was "safe".
If nothing else, all of the ingredients were basically nontoxic. It was
pointed out by others that the glaze would probably leach or "may" leach due
to the low silica content in the mix. The inference then was that the glaze
was not "safe". I am just curious, if I can eat the powdered glaze with a
spoon or drink the liquid glaze out of a cup with no harmful effects, what
difference is it going to make if the glaze will leach a bit when exposed to
the right/wrong conditions? Am I missing something here?
Earl Brunner where it is one of the best two times of the year in Las Vegas
Ron Roy on wed 23 sep 98
Hi Earl,
I posted a message that dealt with this yesterday - it had bounced back for
some reason along with 5 or 6 others - but perhaps an addendum is in order.
Say a glaze is described as food safe - because it has no toxins present -
but is not durable. Some one sees the caveat and assumes they can add
stain, no mater how toxic, to it. That means anything in the stain will
leach under certain conditions and possibly the glaze will change colour
with use as well.
So again - there are two factors that enter into this. The only truly food
safe glaze is a durable glaze when you start messing around with it. In
fact it is possible to make even a durable glaze unstable - say by putting
in more copper oxide or carbonate than the glaze can hold in solution
during cooling. Certainly those glazes (oribe) can change colour in use.
RR
>----------------------------Original message----------------------------
>This past week there was a post about a glaze that someone felt was "safe".
>If nothing else, all of the ingredients were basically nontoxic. It was
>pointed out by others that the glaze would probably leach or "may" leach due
>to the low silica content in the mix. The inference then was that the glaze
>was not "safe". I am just curious, if I can eat the powdered glaze with a
>spoon or drink the liquid glaze out of a cup with no harmful effects, what
>difference is it going to make if the glaze will leach a bit when exposed to
>the right/wrong conditions? Am I missing something here?
>
>Earl Brunner where it is one of the best two times of the year in Las Vegas
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Earl Brunner on thu 24 sep 98
YES!!! I was waiting for someone to get to that! Leachability or not the
glaze as stated was inherently safe BECAUSE nothing was toxic in the glaze as
stated. HOWEVER as Ron points out if you then add colorants (which usually
end up being toxic to a greater or lesser degree) then you change the whole
picture. So yes, a glaze that will leach because it doesn't meet the silica
ratios, should probably be avoided just because you don't know what someone
else is going to do with it, particularly in an open studio setting.
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