Jeff Lawrence on sat 19 jul 97
Okay, another reason I am mad at G.B. is because it gnawed on a new tool.
I mixed up a couple of gallons of Worthington's Clear ^07-^03
Gerstley Borate 55
EPK 30
Flint l5
put it into my brand new pressure pot (I think its galvanized) and a month
later, the pot was toast. Actually dotted with rock-hard squamous warts of
tan crud. I can sand them off but haven't felt that desperate yet...so
they're still on there.
I charge the Gerstley Borate with the condition -- cant imagine the EPK or
the silica doing anything like that. Any hypotheses? Any defenders?
Most of the raku glazes I like are heavy on the G.B....
Jeff
Jeff Lawrence
Sun Dagger Design
ph/fax 505-753-5913
Ron Roy on mon 21 jul 97
I know from bitter experience not to store glazes in metal container. I
think my problem was iron glaze in galvanized garbage can - or was it a
zinc glaze - long long ago. I am sure there are other oxides that find
metal appealing. I think I am recommending plastic for everything.
I also remember, when I was doing raku (1969 - 71), using a glaze which was
80% GB and 20% Neph Sy - I might still have some of it way up on that top
shelf at the back. I think I had to mix it fresh each time - yes I am
ashamed of myself but who knew then - a friend was using a raku glaze with
white lead in it and I can remember we were all just starting to get the
message about it.
I am not saying the following will alleviate problems of storing a glaze
with gerstley borate in a metal container but - If I had a glaze with any
more than 20% GB I would certainly replace any amount over that with a frit
(see Tom Bucks notes with which I concur.) I actually tried to substitute a
frit for the GB using calculation software but found I could not substitute
directly. The reason, mainly, is that Frits all have a substantial amount
of silica and GB doesn't have much. If there is silica in the glaze then
the problem is easily solved but you need to calculate to get it right.
>----------------------------Original message----------------------------
>Okay, another reason I am mad at G.B. is because it gnawed on a new tool.
>
>I mixed up a couple of gallons of Worthington's Clear ^07-^03
>
> Gerstley Borate 55
> EPK 30
> Flint l5
>
>put it into my brand new pressure pot (I think its galvanized) and a month
>later, the pot was toast. Actually dotted with rock-hard squamous warts of
>tan crud. I can sand them off but haven't felt that desperate yet...so
>they're still on there.
>
>I charge the Gerstley Borate with the condition -- cant imagine the EPK or
>the silica doing anything like that. Any hypotheses? Any defenders?
>
>Most of the raku glazes I like are heavy on the G.B....
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Studio: 416-752-7862.
Email ronroy@astral.magic.ca
Home page http://digitalfire.com/education/people/ronroy.htm
| |
|
