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Making Activities Project Five for Schools with Ceramics Facilities: Making Moulds and using them Suitable for Key Stage 3 and up Overview (See also – “Project 4. Press moulds / relief work / repetition / plaster plaques” in the projects for schools without ceramic facilities section) As lot of the work in the exhibition makes use of repetition. This is usually done by using moulds and in particular in this exhibition, by slip casting. The advantage of slip casting is that you can make a lifelike cast of virtually anything, provided you can make a complicated enough mould, and it can be a very exciting technique. The disadvantage is that slip casting and mould making can be messy and complicated and unless you are used to working with plaster / ceramics, I would really only recommend using this technique if you are working with a small group of older pupils – ie, a small Key stage 4 or A level class. You can however use / buy ready made moulds for slip casting, and simple press moulds are much easier to make and use. This work would be suitable for Key Stage 3 pupils and up, and even very small groups of key stage 2. Undercuts You must avoid undercuts when making moulds. If you have an undercut, you will not be able to remove your object from the mould or be able to open a two piece mould. Remember, plaster isn’t flexible like latex. For example, the object in fig 1 in the slip casting section of “Working with Clay and clay-like materials”, will come out easily because there are no undercuts. (A mould like that is called a “one piece drop-out mould”). However, if the shape was like this: it would not drop out because of the undercuts, and the mould would have to be in two pieces. A good example is a mould of a heart. You should be able to make a two piece mould of a heart that will come apart easily, but only if you put the join in the right place. We can see how this works. In Figure 1 the mould will not come apart because of undercuts. Where as in Figure 2, the mould will part easily – no undercuts! The skill in mould making is working out where the joins should be so as to avoid undercuts.