MAKING MOULDS AND CASTS. 



263 



quarter of an inch thick, or as the plaster will make it. Then 

 wipe off the exposed edges of the mould so they will fit snugly 

 together with No. 3. Now mix up a little more plaster, about 

 one -fourth the quantity first used, pour into the hollow, then 

 put on the third piece : tie all tightly together, and turn the 

 mould round and round slowly. This fills the third piece, and 

 holds it in its place. Keep turning the mould slowly, and tap- 

 ping it with the left hand. Leave a little of the plaster on the 

 outside, on a piece of glass or paper, so that you can tell when 

 it gets hard and flinty in the mould. Do not take off the mould 

 until the cast is perfectly hard. 



How TO MAKE A WASTE MOULD. When a soft or fleshy ob- 

 ject is to be cast, 

 one which will 

 yield, and draw 

 out of the mould 

 regardless of un- 

 dercuts, a very 

 quick and satis- 

 factory process 

 (provided a sec- 

 ond copy of the 

 cast will never 

 be wanted) is to 

 make what is called a waste mould. This, with a fleshy sub- 

 ject, is a short cut to a perfect cast, and often saves hours of 

 valuable time. In obtaining casts of mammal heads, legs, or 

 other parts, or casts of fishes and reptiles, it is the method joar 

 excellence. Let us learn the principles of it by making a waste 

 mould and cast of a human hand. 



1. Bed the hand in damp sand (i.e., qce-lialf of it), as shown 

 in the accompanying figure, No. G3. 



2. Give the exposed portion of the hand a good coat of lard 

 oil. 



3. Take two-thirds of a gill of water in a teacup, put into it 

 half a teaspoonful of dry Indian red (to be bought for five cents 

 at any paint store), and mix it up. This is to color sonic plaster 

 with which to make a thin, colored lining for our mould, the 

 purpose of which will be appreciated later on. 



Fio. 63. The Beginning of a Waste Mould. 



