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decorating slip/engobe

updated sun 15 nov 98


Lawrence Carter on fri 13 nov 98

Hi yuo all,
I am an absolute novice to clayart conferencing, either I am asking the
wrong questions or you people out there who pot do not get involved with
crystalline glazing, particularly as I have not received one response to
my question posted on the 6th November 1998.
I have been potting for over ten years and do not consider myself a
novice when talking pots; so I offer a less complicated discussion than
that of crystalline glaze melt point temperature, you could say " To
test the water"
I need a recipe for the application of slip or engobe decoration on
stoneware to be reduction fired to cone 9 over or 1280 degrees
centigrade. My problem is to get the glaze to take over the top of base
glaze -wax resist- coloured glaze. then slip decoration. The slipcurls
up and rolls off the pot- I at my useless efforts am beginning to
I need some ree-eel working advice on this task which escapes me; Please
help .I would like to continue to offer small contributions is there
anyone out there.

Crazy Crystalline Glazer
Lawrence Carter

Craig Martell on sat 14 nov 98

Hello Lawrence:

I remember one of your initial questions about finding the fusion temp of
your crystalline glaze. One way to approach this is to use draw trials.
Make some coils and form them into small circles that will sit upright and
place them in the kiln near a spy so that you can pull them out at different
temperatures. Just glaze the upper part of the coil because of the runny
glaze factor. Watch the pyrometer and pull trials at temps where the glaze
is likely to start fusing. I use draw trials in the salt kiln, and pull
them out with a thin steel rod. Wear gloves!

As for the slip-engobe thing, am I correct that you are placing a slip over
a glaze? If so, the curling that you are getting is normal. Slips will
almost always have a higher clay content than a glaze and will shrink more.
This will cause the curling and crawling. You will need to calcine some or
most of the clay in the slip to get this to work. Multiple application
methods are tricky and crawling and shelling is a common problem. Try to
apply one material over another as soon as the initially applied glaze or
slip loses its sheen but hasn't dried and done all it's shrinking. Timing
can be a critical factor. Applying raw slip to bisque ware is not usually
successful unless you've calcined some of the clay in the slip or reduced
the raw clays considerably. This is a tough one to answer well and I hope
I've helped a bit.

regards, Craig Martell in Oregon