You will need:
Petroleum Jelly (Vaseline)
Moulds
Plaster of Paris
Plastic bowl
Soft cloth
Small paintbrush
Spoon
Ruler
Coarse cloth
Fine sandpaper
Small pointed knife
Epoxy glue
1.
Coat the inside of the moulds with petroleum jelly. Use a soft cloth to rub the jelly carefully into all the ridges and recesses of the mould, then wipe away any excess with a clean sheet of kitchen paper towel.
2.
Pour a small amount of cold water into the pudding basin to a depth of about 2.5cm and, using your hands, sprinkle plaster of Paris on the surface. Don't mix it at this stage; the expanding plaster absorbs the water on its own. Keep adding plaster at intervals until the mixture is the consistency of single cream. Test this by gently mixing it round with your hand. The mixture should be silky smooth and pale grey in colour.
3.
Stand the greased moulds on a flat, level work surface. Working quickly, spoon a small amount of plaster into each mould and brush it all over the surface, making sure you work it into every crevice. Use your finger for this if you prefer. Then. scooping the plaster
up in your cupped hand for the best results, fill the moulds to the top.
4.
Very gently tap each mould on the work surface to make sure that any trapped air bubbles rise to the surface of the plaster, otherwise the finished moulding will be pitted. The plaster starts to set immediately; as it sets, plaster gives off heat so the moulds feel warm to the touch.
You can hold small mouldings in place with a hot
glue gun or with epoxv resin adhesive, but for a
more permanent effect and for larger pieces, fix
them in place with tile or coving adhesive. Whichever method you choose, the mouldings need some support from a strip of masking tape or a couple of panel pins underneath to hold them in position while the adhesive is drying.
5.
When the plaster has hardened slightly and thickened to a fudge-like consistency, carefully smooth off the surface of each mould with a ruler or flat piece of wood. Leave the mouldings to set undisturbed for at least 15 minutes - longer if the pieces are large.
6.
While the plaster mouldings are setting, wash the brush and remove small plaster spills and trimmings from your worktop. Leave any remaining plaster in the pudding basin to set hard, so you can unmould it in the same way as the cast mouldings. Don't pour it away as the plaster may harden and block pipes.
7.
When the plaster feels hard and very warm, lay your hand on top and reverse the mould on to the work surface. Bend the mould slightly, if possible, and the cast should drop out. If not, check the edges are free of excess plaster and use a pointed knife to work carefully round any curves. If necessary, tap the mould edges gently on the worktop.
8.
Discard any damaged casts. Smooth rough edges with a file or sandpaper. If the mouldings are to be fixed in place with adhesive, roughen the backs with sandpaper or a file. Lay the mouldings on a coarse cotton or linen cloth until completely dry - they should be dry enough to paint or seal after 48 hours, but leave them for several days before fixing them in place.
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