[Ansteorra] question on ceramics and its history

[Paul DeLisle]

Stefan:
"Slip" is the term used for liquid plaster (or ceramic.)

In plaster, the slip is poured into a negative mold (also usually made of
plaster, with a seam to allow it to split in two or more pieces); and
allowed to slowly dry (the dry mold wicks the moisture out of the slip,
allowing it to dry slowly from the outer surfaces first.)

In ceramics, the slip is poured into a negative mold; allowed to coat the
inside, and poured back out; creating a hollow positive object (such as a
vase, or a statue.)

As it dries, it it takes on the consistency of wet leather (very fragile),
and then dried mud, or tree bark (not so fragile, but brittle.) At this
stage, it's called "greenware" (because it hasn't been baked in a kiln, or
"fired".) After it dries completely, it is alternately fired, painted,
and/or glazed, to achieve the desired effect.

Alden
(who knows a little about a lot of things...)


> Centurian Giotto commented:
> > I have documentation of plaster molding being used under plates on
> > a kick wheel during throwing to form the smooth inside of the plate
> > and of plaster press molds for "lace woven" plate edges.  Both
> > processes are shown in "Three Books of the Potter's Art", a
> > thirteenth century treatise on pottery techniques.
>
> Oh! Interesting. I'd never thought to consider that if you were wheel
> throwing a plate that you really would want to do that upside down.
>
> I also have a bit on the use of plaster within period, but I don't
> think anyone mentioned anything like this.
> plaster-msg       (16K)  3/17/99    Use of plaster in period.
> References.
>
> I also don't remember anyone mentioning this "Three Books of the
> Potter's Art" treatise before, either.
>
> If you'd care to elaborate on any of this further, I'd love to have
> one or more such articles for the Florilegium. Or even a few messages
> on these subjects to add to the appropriate files if you'd don't feel
> like doing the articles.
>
> Also, for us folks who aren't that familiar with pottery, what do you
> and Mistress Clarissa mean by "slip casting"?
>
> Thanks,
>     Stefan
> --------
> THLord Stefan li Rous    Barony of Bryn Gwlad    Kingdom of Ansteorra
>     Mark S. Harris           Austin, Texas
> StefanliRous at austin.rr.com
> **** See Stefan's Florilegium files at:  http://www.florilegium.org ****
>
>
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