crazing not wanted (help!)

updated sun 18 may 03

Mary Dixon/Steve Stanchfield on fri 16 may 03

Hi everyone
I have been trying to work with what I've got (small starter
kiln and perfectly good over the counter products), going on
my third year in pottery and the process of what I want.

I am making porcelain animal jewelry (slab/handbuilt) with
Runyan's Production Porcelain. BUT I am having trouble with
the underglaze color retention/clear glaze crazing thing.
At first it didn't bug me but now I want a nice clear piece
that keeps its colors when clear glazing.
Here's what I *was* doing:
^6 bisque with Amaco Velvet Underglazes applied, carefully
painted as greenware (I have the Evenheat 810 and I have
only dared fire it to ^7)
^04 glaze with Amaco LF clear glaze, which usually resulted
in crazing (obviously not a COE fit)


In the journey, I have tried many, many combos of cones,
products, arrangements including the following (with the
accompanying notes:

^6 bisque with Amaco Velvet Underglazes applied as greenware

^02 glaze with Amaco LF clear glaze (resulted in smooth
surface but you could see tiny bubbling all over and in
design indentations, some crazing)

^6 bisque (w/Velvets, etc same as above)
^3 glaze with Amaco LF clear glaze (as an experiment; was
still glossy but still made tiny bubbling look)

All sorts of low fire bisque cones (^02, ^03, ^04, ^05)
w/Velvets applied as greenware
^5 or ^6 glaze with Amaco HF clear glaze (color burnout of
the Velvets every time. Most colors faded or turned into
some other color in reaction to the HF clear glaze. Only
orange stayed true but no crazing, at least.)

All sorts of low fire bisque cones (same as above) w/Vevets
applied afterwards as bisqueware
^5 or ^6 glaze with Amaco HF clear glaze (same color loss
result and no crazing)

^6 bisque w/Velvets applied afterwards as bisqueware
^5 glaze with Amaco HF clear glaze (same color loss result
and no crazing)

My next experiment will be:
^6 bisque w/Velvets applied as greenware
^03 glaze with Amaco LF clear glaze with test piece divided
as follows: 1) LF clear glaze applied w/2 coats instead of
three, 2) Amaco LF clear and Amaco LF matte clear mixed
50/50 and 3) Amaco matte clear, 2 coats instead of three (so
details show through)

If anyone out there has any suggestions on how I can correct
my problems and live a happier jewelry life without
starvation I would be indebted to you forever and will seek
out your work to buy someday, I promise!!

Sorry so long, I figured more details would be better when
asking for help from the more experienced potters out there
who remember what this stage felt like!

THANKS!!

Mary

Bobbruch1@AOL.COM on sat 17 may 03

Mary writes: <<<From: Mary Dixon/Steve Stanchfield
Subject: Crazing NOT wanted (help!)

<<<perfectly good over the counter products), going on my third year in pottery
and the process of what I want. I am making porcelain animal jewelry
(slab/handbuilt) with Runyan's Production Porcelain. BUT I am having trouble
with the underglaze color retention/clear glaze crazing thing. At first it
didn't bug me but now I want a nice clear piece that keeps its colors when
clear glazing.

Mary: I tried Amaco velvets at one point and had trouble with their adhering
to the clay body. Not exactly the same problem that you are having, but my
solution might work for you. I started testing adding small amounts of the
clear glaze that I am using as a liner into the velvets. This seemed to solve
any problems that I had, and for matte surfaces, I didn't need to put a glaze
over them. Amaco also has a newer product, it may be called "majolica velvet
underglaze", but I am not sure. This has a glossier surface than the velvets,
and you can either put a clear over them or leave them as is. A clear over
them will have an impact, but not to the same degree as with the regular
velvets, and you may be satisfied with using them on their own.

Also, you may be at the point where you want to consider making your own
clear glazes. (JMHO) I think that you can find a number of excellent
commercial clay bodies to use, but glazes may be another matter.

Bob Bruch