August 5, 2009
An Introduction to Slip Casting Ceramics with Multi-Piece Molds
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For the past year, potter Linda Gates has been decorating her ceramic surfaces using commercial digital decals, with imagery of everyday objects from the 1950s, including the paper dolls of that era. It was a project she started during her studies in the ceramic design program at Bath Spa University in England. Gates prefers to slip cast her forms so that the surfaces are as smooth as possible for the decal application. Today, Gates walks us through the slip-casting process for one of her jug forms using a four-piece plaster mold for the body and a two-piece plaster mold for the handle. - Jennifer Harnetty, editor. |
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With a little modification to the original jug design, I made new plaster molds, one for the handle (shown at left) and the other for the body of the form. |
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The mold for the body of the jug (shown at left) is made in four parts - the two sides, the base, and the reservoir. |
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Download your free copy of the Buyers Guide to Ceramic Supplies and Materials to learn where slip-casting materials can be purchased. |
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To prevent leaks when pouring the casting slip, secure the parts firmly together with strong bands cut from rubber inner tubes. If you design your mold to include a reservoir, which makes it easier to maintain an even rim thickness, fill the mold to halfway up the reservoir wall using commercial earthenware casting slip. As the porous mold absorbs the water from the clay, the excess is drawn from the reservoir. |
| The handle mold is also filled with casting slip. Once the slip is the desired thickness (check by blowing on the edge of the mold where the slip and plaster meet), pour the extra casting slip back into the container and leave the mold inverted at an angle to drain into a bucket. Placing it at an angle avoids stalactites of clay forming on the bottom of the piece. Tip: To achieve even thickness between multiple casts, it is a good idea to time the first casting and use this as a guideline. | |
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When the mold is well drained and the sheen has gone from the wet casting slip (typically about 20 minutes), remove only the reservoir portion from the jug mold, trim the excess clay from the top and clean it up with a damp sponge. I leave the rest of the mold intact for a further hour or so for the form to firm up for easier handling. |
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Both molds are then disassembled and the jug form and handle carefully removed. Both component parts are cleaned up with a fettling knife and damp sponge. The handle is attached, and the form is covered in plastic for 24 hours to ensure a secure join. |
Tags: Ceramic Molds, plaster
Dr. David | August 5th, 2009 at 2:35 pm
Very interesting process. I have often been interested in making a mold of pottery pieces that I have hand built. Can you offer some references on how to make plaster molds?
Lori | August 5th, 2009 at 2:45 pm
Yes, I would also like to see mold making. How do you get those registration holes and how do you know where to break up the mold? And how do you do that?
Joe | August 5th, 2009 at 4:30 pm
Very Cool Stuff, Linda Gates. Quite different from the “Engage” bottles I have from your days at Irvine Fine Arts Center. I like the new work just as well. I found more online as well. Joe Viers
Donna | August 5th, 2009 at 5:13 pm
Is there a good resource for the decals? Can you make your own?
joy | August 5th, 2009 at 7:15 pm
I’ve just purchased The Clay Lovers Guide to Making Molds & The Essential Guide to Mold Making and Slip Casting. I’d love to see a (2) piece mold making video!
Linda | August 5th, 2009 at 8:57 pm
I’d like to see a video on making a mold of a stein. I would imagine it would have to be at least a 4 piece mold. The bottom, and three pieces for the sides, so as not to destroy any low relief carving around the stein. I have the Lark book on making molds but there is not enough information given.
Genevieve | August 5th, 2009 at 9:54 pm
To Dr David who asked for info on how to make molds: you just have to click on the right of this article, on the item “making ceramic molds” inside the list “Pottery making techniques”.
Genevieve | August 5th, 2009 at 9:58 pm
Also, go to your local library, there are many books on pottery techniques where you’ll find details on how to make complicated molds. Plus there must be all sorts of resources online.
aswa | August 7th, 2009 at 5:47 am
Too good
Carla | August 9th, 2009 at 4:53 am
Thank you for this great article. You indicate using commercially prepared slip. I am wondering if it is possible to make a good casting slip from my recycled and reclaimed clay. Do you know what would be the indicators for an adequate slip if I made it myself?
JEAN | August 9th, 2009 at 7:56 am
I am interested in the decal part of this post…I would like to make a small number of commemorative mugs for a local event, and thought decals of an old photo would be great. Can any one help me with this? Can I make my own on a copier? Resources? In simple words? Thanks!
Michelle | August 12th, 2009 at 3:59 pm
I am intersted in a pottery class in the future
Jennifer | August 13th, 2009 at 8:42 am
To those interested in learning more about applying decals, there are several articles (even a how to video!) in the Ceramic Arts Daily Features Archives on this subject. Search for decals in the search field in the upper right hand corner of this page and you’ll find them! Happy decaling! -editor.
Dan | September 5th, 2009 at 7:04 pm
I make my own decals using a laser printer and decal paper that you apply and heat set in a oven at 350% they are microwave and dishwasher safe.