Martin Howard on thu 15 aug 02
Antoinette says:- you will have to add some glaze components to your slip
and change it to an englobe.
I fire to cones 1-3. The white clay used for the slips matches the base
earthenware clay.
By putting the glaze straight on top of the slip, both are firing together
and in effect, forming an engobe within the kiln.
This may be the logical reason for me not finding problems with this method,
so far.
Martin Howard
Webbs Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
http://www.webbscottage.co.uk
Updated 6th July 2002
Timakia@AOL.COM on fri 16 aug 02
That sounds fair Martin. If your slip and glaze becomes one it can work. The
fluxes in your glaze is probably also very active. I am wondering what
reaction you will get if you mix your glaze and slip. I do not know much
about slip glazes, but depending on what results you need, I would do some
more tests for incase you run into trouble again. Years ago I used
transparent glaze in some of my colorings. That was before I had receipes to
mix slips and englobes. It worked well then.
Take care.
Antoinette Badenhorst
http://hometown.aol.com/timakia
105 Westwood circle
Saltillo, MS
38866
vince pitelka on fri 16 aug 02
> I fire to cones 1-3. The white clay used for the slips matches the base
> earthenware clay.
> By putting the glaze straight on top of the slip, both are firing together
> and in effect, forming an engobe within the kiln.
> This may be the logical reason for me not finding problems with this
method,
> so far.
Martin -
I really have no idea why you are not encountering problems with that slip,
because the above logic does not necessarily work. A properly formulated
engobe will have higher percentages of non-plastics to reduce drying
shrinkage, plus some low-melting fluxes (particularly borax) that bond to
the claybody early in the firing. There is no way that a glaze over the
slip will accomplish the same thing.
Slips can be fickle. A recipe that works great on one claybody may not
necessarily work at all for a very similar claybody. It is apparent that
you have been lucky, but you must keep in mind that a straight clay slip
simply cannot produce as strong a slip-body interface when applied to
bone-dry or bisque-ware. You may encounter problems at any time. If it
were me, I would adjust the slip recipe to a proper engobe for application
to bisqueware.
Best wishes -
- Vince
Vince Pitelka
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
Home - vpitelka@worldnet.att.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
http://www.craftcenter.tntech.edu/
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