Monday, July 1, 2013

Wheel Thrown Slab Hump Mold Plates - Pottery Making Tip

What? Huh? Throwing slabs on the hump sounds really weird.  Here's what I have going on.
 I poured a plaster hump mold and used E-6000 to attach it to an old bat.   I know many potters really don't like using plaster for bats or hump molds, but if the plaster is mixed and poured right, it's awesome and safe to use.

I rolled a thicker slab and placed it on the hump mold.


Starting at the center, I used a sponge to compress the clay onto the mold.  

Next moved clay from the center and up from the side to form a foot ring.  No trimming necessary :) 

This plate isn't ideal for my stamped decorations, so I decided to have a little slip-trailing fun. 


Now the big question is..  will this thrown slab plate warp in the kiln? 

Check out these Youtube videos showing this technique!  Steve Booton and Mark Lueders 


All designs, photos and content herein are owned by and ©copyright Cindy Gilliland.

13 comments:

  1. Brilliant, I bet it will work out great.

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    1. I'm not sure that I can call it "wheel thrown" even though it is partially wheel thrown. I made a pedestal cake stand using this technique.. Easiest cake stand I've ever made.

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  2. In the 80's my business partner at the time and I did slabs thrown over plaster as well as slabs rolled around cardboard tubes. We had many humps because we had large accounts such as Macy's. The only time that we experienced warping was when we removed the slabs from the molds too early in the drying process. Otherwise, even large bowls and platters came out fine. We put a bat on the upside down foot and flipped the pots directly onto a flat surface without lifting it by one edge or another. I still have many of those dishes. They were a great decorating surface and we did floral patterns with Mason stains.

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    1. Hi Christine, Great info, Thanks! I would love to see some of the pieces you made for Macy's. These plates are the perfect canvas. My mind is going in so many directions.

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  3. That's how I do my leaves
    http://baumanstoneware.blogspot.com/2011/03/sixty-minute-man.html

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  4. HI, I've been making plates this way for several years now and have had very few problems with the process. I do not glue my plaster bats to anything. When making them I make sure they are very flat and smooth on the surface that will be on my wheel head. When I am ready to throw I simply put down a thin layer of smooth clay slurry and center the bat on the wheel head. The sucking action of the plaster keeps it attached to the wheel head. When I'm ready to take the bat off the wheel head I slip an old paring knife between the bat and wheel head and twist it and that breaks the seal.

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    1. That's fantastic. I'm glad the feedback confirms this technique is tried and true. My thought in gluing the plaster mold to the bat was to protect the hump mold from chipping while putting it on and taking it off the wheel head and also when I put it on the rack to dry. So far it's working excellent.

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  5. huh- this is new to me. do you just let it get VERY leather hard before removing it from the plaster mold? Haven't used plaster molds much. Guess in time it just pops off it on its own?

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    1. Hi Amy, The slab plate doesn't stick to the hump mold.

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  6. And the answer is? (did it warp)

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    1. I made 5 of them. They didn't warp, but you could see a slight rise where the foot was thrown.

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  7. This is great, I think i'll make a few. Have you tried making the plates by just centering a ball of clay instead of making the slab? Does is show rings from the slurry that occurs from the centering process?

    Do you think the plate dries slower because the plaster is glued to a bat so it cant dry from both sides?

    I think i may try some kind of keyed bottom bat instead. But your method is so easy it may be worth just waiting a little longer.

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    1. Hi Sarah,
      - I actually haven't tried throwing a ball of clay with the molds.
      - The compression lines don't show through to the top of the plate.
      - I haven't had an issue with the mold becoming over saturated and slowed drying. I live in a very dry climate, which may help.
      - You could certainly use the key fit molds. They are great too.
      Have fun!

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