Susan Germain on sat 13 sep 97
I am having trouble applying gold and silver lusters to my work. It seems
that my glaze is crackling so the lusters come out rather dull.
I use a porcelain clay because I like the crispness I can get in the
carving. I do not fire to maturation, because it becomes vitreous and
difficult to apply pigments smoothly. I usually just go to 06 or 04.
Bought a new jug of glaze, thinking my old stuff might be the problem, and
my glaze still crackles. Nope, still crackling.
Anyone have any clues as to what is happening and therefore how I can
correct it? People are loving getting my "blems" for half price, but I
want to fix it!
I'd especially like to know when porcelain will mature, but not become
vitreous. Or should I just go out and buy regular white clay?
Thanks in advance!
Susan
Grace Liu on sun 14 sep 97
Susan Germain wrote:
>
> ----------------------------Original message----------------------------
> I am having trouble applying gold and silver lusters to my work. It seems
> that my glaze is crackling so the lusters come out rather dull.
>
> I use a porcelain clay because I like the crispness I can get in the
> carving. I do not fire to maturation, because it becomes vitreous and
> difficult to apply pigments smoothly. I usually just go to 06 or 04.
>
> Bought a new jug of glaze, thinking my old stuff might be the problem, and
> my glaze still crackles. Nope, still crackling.
>
> Anyone have any clues as to what is happening and therefore how I can
> correct it? People are loving getting my "blems" for half price, but I
> want to fix it!
>
> I'd especially like to know when porcelain will mature, but not become
> vitreous. Or should I just go out and buy regular white clay?
>
> Thanks in advance!
> Susan
Susan,
We've had numberous problems with glaze crazing on our porcelain (we
only work with porcelain). In our experience, the only (expedient) way
to resolve the crazing (without having to adjust the glaze composition)
is to fire the porcelain body to maturation. We fire to cone 8 or 9, &
soak for 2 hours at the top. Our glaze is really sensitive too, that if
the body isn't fired completely to maturation, sometimes crazing occurs
days later! Truly a pain. I won't attempt to explain why this occurs (I
only have a basic understanding of the real technical aspects), so I'll
leave that up to the techies on the forum.
There could be a way to change the composition of the glaze, but if
you're buying it off the shelf, that could be difficult.
Regarding decorating with pigments, I presume you're using some sort of
underglaze? We haven't tried that yet. We've been using on-glaze colors
to decorate on the whiteware.
The colors apply very evenly. We also use gold, matt gold, matt silver
which we apply as the last and lowest firing (at cone 018 to 017). You
have to be careful not to fire that last firing too high, ie. avoid
firing to the temperature where the glaze starts to melt, because then
you'll get small fissures in the gold/silver.
Hope this helps.
grace
| |
|
