Casts 77 



tween the halves because the fins will be too thick and therefore 

 appear artificial. Do not apply an excessive amount of plastic 

 or you will have to keep wiping the sides of the mold, and this 

 makes a messy job. 



When the plastic has set, tap a chisel here and there between 

 the halves of the mold until they separate. If difficulty is en- 

 countered in taking apart the mold, it is an indication that the 

 separator was too thin or did not entirely cover the mold sur- 

 face. Both sides of the mold will never release from the cast fin 

 simultaneously. When one half is removed, the other half will 

 still hold the cast fin. Therefore, it is necessary to insert a chisel 

 gently around the cast in order to pry it away from the mold. 

 Immersion of the mold and cast in hot water, or application of 

 heat, will soften the cast fin so that its removal can be accom- 

 plished without breaking. 



Clean the casts, wipe off any separator wax with a cloth 

 dipped in turpentine, and wash them well in soap and warm 

 water. Then outline the fins with a pencil and cut them out 

 with a jig saw. Be sure an extension of the base of the fin re- 

 mains. Before placing the fins, make sure that you secure a 

 lifelike curvature. This applies to the tail and the fins on the 

 main cast as well as to those that have been cast separately. 

 Let hot water run over them until they become pliable (the 

 pectoral and ventral fins can be held in a small pail of hot 

 water ) . As you remove them from the hot water, shape them 

 quickly and hold them in position with finger pressure until 

 cool. When cool they again become rigid but remain in their 

 new shape. The fins can be heated and reshaped any number 

 of times. I use cloth-lined rubber gloves so that my fingers will 

 not get burned. Under no circumstances attempt to curve the 

 fins when they are not thoroughly heated and pliable, or they 

 will crack. 



Now place the pectoral and ventral fins. If they don't fit into 

 their respective holes easily, file away more of the area. Mix 

 a small batch of formula No. 2, place some around the base of 

 the fins, and insert them. A support is necessary to hold the 

 fins in position until the plastic at their bases has set hard. 



