A mold is an inlaid copy of an object and can consist of one or many sections and is used to reproduce work in clay or clay slip. In pottery, molds are used to reproduce many products, plates, jars, statues, etc. A mold is filled with slip or clay and left to dry. When dry, they are separated and you have a copy of the original object, which is known as a cast. Molds are important in pottery as they can produce special pieces, quicker and more accurately, that could not be made by hand.
MOLDS: THE BASIC WAY OF WORKINGWITH A MOLD OF ONE PIECE
1) Make in clay the shape you want to make the mold.
2) Put it on a wooden bat and around it build up a wall, with wooden boards, slabs of clay, sheets of rubber or plastic.
3) Leave a space of 3cm between the wall and the clay object, which is the width of the wall of the mold once cast.
4) This size depends on the size of what is being made; the larger it is the stronger the walls must be.
5) Where the sections of the walls join each other or the bat, they must be sealed firmly together with coils of clay on the outside and inside. The inside joints are smoothed off so the mold will have even surface
6) Prepare the plaster: In a bucket put the amount of water needed for the mold you are going to make. Tip the plaster slowly into it and leave it for a few minutes so they can integrate.
7) With your hand, wearing a plastic glove or a large strong wooden spoon, stir it slowly so it becomes smooth, without any lumps. While doing this you will notice that the viscosity of the liquid is thickening.
8) When it is like cream, pour it slowly into the mold, over the object, filling every corner, until the lair on top becomes thick enough to form a strong floor.
9) When the plaster has hardened, take off the walls, turn it upside down and remove the bat and then the clay. Level off any rough parts then smooth and clean it with a damp sponge.