Plasterkraft

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Plasterkraft covers both of our plaster-related activities.

Who doesn't enjoy making stuff out of Lego or Mechano or any of the dozens of similar children's toys? Well, imagine a building block set with over 900 different shaped blocks and an unlimited number of each block and you'll begin to see the possibilities of our Plasterkraft modelling activity!

This activity involves gluing blocks together to make some sort of structure and then painting the result. It sounds simple but with the range of blocks available the possibilities are endless. We have dozens of ready-to-build kits available with complete plans and instructions or you can build from scratch. Once assembled the pieces are permanent. The blocks cannot be disassembled and reused.

We also have a series of latex moulds that are used to create plaster figurines for painting. These figurines are usually quite small, somewhere between five and fifteen centimeters tall. Casting these moulds successfully is moderately challenging but the results are well worth the effort.

Broadly speaking Plasterkraft involves making something out of plaster and painting it. Most children will have experienced something similar at school or a hosted birthday party. How then does our Plasterkraft activity differ from what most children have experienced?

Plaster

The cheapest plaster you can buy is Plaster of Paris. It has a dry compression strength of around 2,000 psi. The water to plaster ratio is around 70 parts water to 100 parts plaster. The end result is a cast that chips and cracks easily, absorbs paint like a sponge, and shrinks extensively as it dries. In our Plasterkraft activity we use Ultracal 30 rather than Plaster of Paris. It is a gypsum cement with a dry compression strength of 6,000 psi. The water to plaster ratio is around 38 parts water to 100 parts plaster. The end result is a cast that is unlikely to break if dropped onto the floor, handles paint well, and doesn't shrink much as it dries in the mould. Ultracal 30 produces a professional cast every time and is safe to use.

Moulds

There are three types of materials used in making moulds -- plastic, latex rubber, and silicone. The quality of a mould is defined by the amount of surface detail that can be transferred onto the cast. Plastic moulds are the cheapest to produce. The level of detail is low. Latex and silicone produce exceptional moulds. All of the moulds we use in the Plasterkraft activity are either latex or silicone.

Paint

Each layer of paint applied to a cast obscures some level of detail from the surface of the cast. In painting a cast the objective then is to apply as little paint as possible while still producing a good result. Using a plaster with a hard surface reduces paint absorption and thus ensures that fewer coats are required to get a good, even colour. Yet the paints themselves remain critical. We use an airbrush to undercoat the casts. This produces an even coat the reaches even the most recessed areas of the cast. We use the finest acrylic hobby paints to complete the painting of the plaster casts.

In our Plasterkraft activity children have at their disposal everything needed to produce shop-quality plaster casts.

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