Question from a Non-Maker of ceramics

Not having the mold in front of me, my best guess is that you are referring to the pour hole. Ceramics made from molds use a liquefied clay called slip. It is poured into the mold through the pour hole, which is mostly in the bottom. The piece is allowed to sit for a time, while the water is absorbed into the plaster, leaving the clay behind. Depending on the piece, this could be a matter of about a minute (with some very delicate Christmas tree ornaments) to half an hour or longer. The time the slip stays in the mold also depends on how frequently the mold is poured and the humidity of the room. Once the requisite time has elapsed, the mold is tipped over, and the unused slip is allowed to drain from the mold. It must then be allowed to dry a bit before it can be removed from the mold, and that time is once again dependent on many factors. When the piece is dry enough, the mold is opened, and the piece - which is called 'leatherware' due to its' consistency at this point - can be removed carefully. It is then set aside to dry completely. Once dry, it is called 'greenware'. The seams left by the mold, as well as any imperfections on the piece, can be carefully removed at this stage. It is fired to maturity - depending on the clay - and is then called 'bisque'. It can then be decorated in any number of ways, using any number of techniques.

Hope this helps... :-)

Susan

Susan, thanks so much for trying to help me.

I may not be using the correct terminology with the word "mold" as I mean the product (the greenware?) has a hole in the bottom, not the recepticle for the slip. For example, a china salt shaker will have a small hole in the bottom to pour in the salt, but so do some china figurines, and they don't need anything to be poured in.

My particular collectible, hatpin holders, looks very much like sugar or talcum shakers from the same period. Some people say that if there is a large hole in the bottom, the object must not have been meant to be a hatpin holder since hatpin holders didn't require an opening in the bottom, but talcum/sugar shakers did. Others say that the manufacturers used the same general design for both objects, and the hole was part of that manufacturing process, but I don't know what part of the process that would be.

I put up two pictures of holders that are very similar at

Frankie:

I can't add anything to Susan's excellent explanation of the slip-casting process. But I think I can clear up your confusion. Pieces made by slip casting necessarily have thin walls, thickness limited by the amount of clay that can have its water absorbed by contact with the plaster mold walls. When you pour a mold full of slip, the stuff in the middle stays liquid and has to be poured out somewhere after the walls are thick enough, hence the pour hole. You couldn't make a piece by pouring it full of slip and just letting it dry that way; not only would it take a looong time, but it would almost certainly crack from uneven drying. In general, items made from clay need to be fairly thin; anything over a half-inch or so is "pushing it". Thick sculptural pieces, that are built up by hand instead of slip casting, must be made with hollowed-out sections. With slip casting the pieces are naturally hollow by the nature of pouring the unused slip back out the puor hole.

Hope that helps!

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

The hole is from the pour hole, the one on the right probably had the hole covered over for the final firing. Most poured pieces have a hole somewhere, even if the main hole is covered up, to allow gases to escape during firing. They probably cleaned out the top holes, then sealed up the bottom hole.

That's my guess.

Maybe i can still clarify this issue some more. Most slipcast ware are dishes, vases, mugs, pitchers or such, and they are open at the top anyway, so you never see a pourhole, you just pout the excess slip out through the top. Since the manufacturer wanted you hatpin holders closed at the top, the pourhole had to be somewhere, so naturally it is on the bottom. As Bob already mentioned, the second piece has probably been covered over afterwards.

Monika

Thank you all so much for taking time to help me understand. I believe I do now. The fact that the pourhole in the bottom was present in all the pieces and had to be covered over in an extra step after the first firing leads me to believe that some manufacturers likely skipped this step and allowed the item to be sold as either a shaker or a holder, whatever they needed to supply at the time.

Can't thank you all enough!