WASTE MOULDS IN PLASTER 237 



3. By glue moulds. 



4. By gutta-percha moulds. 



5. By ordinary wax moulds. 



6. By paraffin wax moulds. 



Waste Moulds in Plaster. 



These, so called because they are ultimately broken away 

 piecemeal and only admit of one copy being taken, are 

 commonly managed thus : ^ — 



If the work is a medallion — and perhaps it will be as well to make 

 your first mould as a trial one on a piece of clay, roughly formed like 

 one — the work is easy. 



First brush over the groundwork all round with the moulding 

 composition. Mix a little of the red powder with some water into a 

 paste in a basin, then add more water until the basin is three parts full, 

 put your plaster in until it appears as a sort of hill in the basin with 

 some water all round, beat it up with the spatula, and pour or spread 

 it over the model, say to the thickness of an inch, or nearly so, all 

 round and over it. 



Let this set ; it will be better that it is not touched for an hour 

 or so. 



Then lift it up, and it will relieve from the groundwork ; you can 

 now pick out the clay. 



Soak it for about ten minutes in the pan of water; then, while 

 in the water, brush it carefully, so as, while leaving it clean, none of the 

 fine parts are worn away. 



Now place it on the table, and, to take the cast, mix your plaster ; 

 then see that there is no water left in the mould, which should only 

 seem just shining with the damp. 



Pour some of the plaster in, shake it gently, lay the mould down 

 and fill up with the plaster. 



Let it rest for, say, an hour or longer, then turn it over, take your 

 mallet and chisels and gently cut and break away the mould, which is 

 no longer of any use, and is for that reason called a waste mould. 



' A Guide to Modelling in Clay and Wax, etc., by Morton Edwards, pp. 46, 47. 



