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Molds make it possible to repeat patterns and forms for a variety of reasons. For thousands of years, potters have used molds both for forming and decorating and often both have been accomplished at the same time.  Whether you choose to try press molds with slabs of clay or slip-casting molds for slip-cast pieces, you’ll discover that making ceramic molds provide a way to create uniform pieces that can save you time and provide you with the means to concentrate on surface decorations. 

 

If you’re interested in exploring the world of making plaster molds for slip casting or handbuilding, Ceramic Mold Making Techniques: Tips for Making Plaster, Bisque, and Styrofoam Molds, Making and Using Casting Slip, and Decorating Ceramic Surfaces is a great place to start! Check out this excerpt:

 

Making Prototypes for Mold Making and Slip Casting

 

click to enlarge!

Each new piece begins with a prototype, generally made of wood or MDF, from which I make a plaster mold. The prototypes can be made from clay, but I prefer using wood for its durability. I’m not the savviest mold maker, so if at some point I have an accident during the mold-making process, the prototype is safe and intact. I’ve also found that making prototypes from wood is great for achieving sharp, transitional lines and edges (figure 1).

Once I’ve settled on a design, I produce two scale drawings—one illustrating the side view or profile, which includes the number of stacked pieces of MDF I will need to make the model, and one illustrating the top view. Using the first drawing as a blueprint, disks of MDF are cut, glued together, stacked, and turned on a lathe to make a solid round form whose shape is close to the side profile of the finished piece (figure 2). Tip: You can use a Surform tool to shape the MDF if you do not have a lathe. The second drawing works as a cutting template that is glued to the top of the form (see figure 2).

 

Using a band saw, I cut into the shape of the form, carefully following the outside edges of the glued-on template. The sides of the form are then sanded smooth to erase any irregularities from sawing. Finally, the prototype is sealed with one coat of Minwax Sanding Sealer and two coats of polyurethane.

 

The casting slip I use has a 16% shrinkage rate so the prototype must be made appropriately larger to accommodate the final size of the pot. Always test the shrinkage rate of your casting slip before making the prototype.

 

Making the Plaster Mold

 

When making plaster molds, it’s important to remember that slip casting, like any other building method, is strictly a means to a desired end. It doesn’t have to be an overly technical venture and, depending on the form, can be quite easy. I’ve learned plaster mold making simply by reading books on the subject, and by asking for help from others.

 

The biggest trick to making plaster molds is figuring out the number of parts to cast. Most of my molds are made with four parts—a bottom, two sides, and a top piece used as a pouring gate or slip reservoir. Before I make a mold, I take my prototype and draw seam lines on it with a black marker so that I know how many parts I will need for the mold (figure 3). Then I add a clay slab to the top of the prototype for a pouring gate (see figure 4). By making my pouring gate just a little taller than need be, I can control the quality of the rim after the piece has been cast.

 

Next, I embed the form into a block of clay up to the seam lines marking off the first section of the mold, set up cottle boards, seal the seams between the blocking clay and the cottles, and pour the plaster. Parts of the blocking clay are removed as I’m ready to cast successive sections. The image shows the mold halfway through the casting process, with the bottom and first side cast, and the second side and slip reservoir or pouring gate still to be cast (figure 4). Note that the location of the seams has been planned so that they correspond to edges or places where planes and curves shift, rather than flat faces of the form. This makes them easier to clean up, and makes them less noticeable in the finished form. 

 

This process and more are covered in Andrew Gilliatt’s DVD Layers of Color: Exploring Form and Surface Pattern in Slip-Cast Pottery, which is available in the Ceramic Arts Daily Bookstore.

 

download freebie

 

Ceramic Mold Making Techniques: Tips for Making Plaster Molds and Slip Casting Clay
also includes the following:


 
 

How to Make a Model and a Mold for Slip Casting
by Andrew Gilliatt

 

Learn how to make a model for a shape that you create a mold from. Whether simple or complex, you’ll need to follow the same steps for figuring out to make an original model then determining the best way to cast the mold pieces. 

   
 

How to Make Slip-Cast Vessels and Decorate them with Homemade Decals
by Linda Gates

 

One of the advantages of slip-cast work is the smooth surface, which is perfect for adding decals. Linda Gates shows you how to slip-cast smooth pieces then how to create decals and apply them.

   
 

How to Make a Tile Press Mold
by Ursula Hargens

 

Ursula Hargens was looking for larger surfaces to decorate so she came up with a tile design that suited her needs. Her deep tiles are press molded in a plaster mold and feature some unusual shapes that she plays with to create negative spaces.

   
 

 

Creating a Slump Mold with Styrofoam

by Ben Carter

 

Ben Carter loves working with earthenware and he’s an innovator in creating really cool forms using a Styrofoam slump mold. Without a doubt, Styrofoam molds are the easiest molds to make and they offer a tremendous amount of flexibility.

 

   
 

Making Bisque Molds with Texture

by Nancy Zoller

 

Before the invention of plaster or Styrofoam, the main mold making material was bisque-fired clay. Create your own unique forms from clay and surfaces then easily repeat them over and over again. You’re just a bisque fire away from getting started.

 

 download freebie

 

About Ceramic Arts Daily:
Ceramic Arts Daily is a free online website and newsletter written and produced for the benefit of potters and ceramic artists worldwide. The newsletter features both renowned and emerging artists, their work, techniques and artistic perspectives. Regular features include tips and techniques designed to help every artist expand their skill set and widen their artistic horizons. Ceramic Arts Daily also delivers video tips, in which potters and ceramic artists demonstrate various projects and processes. Think of them as e-workshops!

 

Ceramic Arts Daily is designed to be interactive, inviting your comments and fostering a community in which each person can contribute to the growth of their own and others’ skills. You may be surprised at what you learn!

 

Ceramic artists on Ceramic Arts Daily know what ceramic art is all about – from functional pottery to abstract ceramic sculpture. This is about community. You’ll be drawn in by artists’ stories, inspired by their work and find confidence to try some of their techniques. With Ceramic Arts Daily, you’ll learn a little bit of everything. Then you can choose the techniques you enjoy the most to create something new!

 

So start today by downloading our free Ceramic Mold Making Techniques: Tips for Making Plaster Molds and Slip Casting Clay. Then, get ready for Ceramic Arts Daily to introduce you to new artists and show you new techniques!


9 Comments on "Ceramic Mold Making Techniques: Tips for Making Plaster, Bisque, and Styrofoam Molds, Making and Using Casting Slip, and Decorating Ceramic Surfaces"

  1. Sean December 7, 2014 at 2:52 am -
    The guide is really informative and useful. Thanks so much for providing this for free. I understand that the casting is done when the plaster mold absorbs the water from the casting slip. Does that mean the plaster mold can be used for only 1 cast? Thanks!
  2. Amanda Morris February 17, 2014 at 3:12 pm -
    Hi I’m trying to download the mould making freebie but everytime I click download it is giving me the ceramictiles info. Can someone give me a correct link please thanks Amanda
  3. Julia Douvia December 22, 2013 at 7:38 pm -
    I would like to join but I just got this phone for Christmas and I am not good at it or spelling please forgive me thank you sincerely Julia Douvia
  4. RAHMATU YUNUSA SHARIFF April 2, 2013 at 4:38 am -
    thanks for including me as a member of ceramic daily. Please can you assist me to further my masters study at cheap school fee at one the university.
  5. RAHMATU YUNUSA SHARIFF April 2, 2013 at 4:37 am -
    thanks for including me as a member of ceramic daily. Please can you assist me to further my masters study at cheap school fee at one the uni versity.
  6. littlec@PAULBUNYAN.NET February 20, 2013 at 2:54 pm -
    Thank you so much for posting the video. But……. I need a little more help. I have thrown some difficult forms (for me) and would like to be able to slip cast a few. I have, in the past, before arthristis and old age, made my own molds and know that what I want done is only a two part mold. I do not want to make thousands of one shape, so I dont really want a master mold that makes many molds. I want one plaster mold so I can make a “few” of the same shape. My problem is, I am not able to find a mold maker whose motto is “no job too big or to small” Can you help?
  7. Celina February 22, 2012 at 7:22 pm -
    Dear Meshack Masuku: Once you can read English, I would gladly send you for free a basic and elemental training book for wheel throwing if you give me your postal address. You may prefer to do it through Ceramic Art Daily E-mail address. Cheers!
  8. okoh February 14, 2012 at 4:55 am -
    i really appreciate ur ceramic work, it worth commendable.i will be glad if i can get a brochure of ur school program.thanks
  9. meshack November 16, 2011 at 12:30 pm -
    High everyone this is Meshack Masuku from Emzansi. Thank you guys for all the wonderful tips and tehniques one wishes that there is always ample time to try it all. I would like to appeal to you all those who feel they an and those who knows where to refer. In South Afria we do not have a good progranm for training eramisists, I am involved with a number of ommunity members that needs to be trained so that they an take part in the clay mineral for their artisti talents and make a living out of it it does not mater how small. we have a vast rural ommuinity all over South Africa that needs to be natured in the clay matter. I am looking for a fitting program that an produce a lerned individual in a community based enviroment. We want to produce all kinds of products so I need a training manual that an be acredited when succesfully completed. Please guys help. Regards Meshack Masuku ell:+27826299590.

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