Plaster Molds 35 



Find some soil fairly free from rocks and debris for the shelf 

 around the fish. Add enough water to the soil so that it will 

 remain where placed ( Fig. 29 ) . A seashore beach is an excel- 

 lent spot for this type of work. Plenty of salt water is at hand 

 to mix with the sand, and the plaster bowls can be cleaned easily 

 directly in the surf. Remember, though that, fresh water is still 

 necessary for mixing the plaster. 



The advantage of working out of doors is that the plaster 

 bowls can be cleaned without fuss, and any excess plaster can 

 be dumped on a pile. And of course there is no worry of decorat- 

 ing the floor, walls, or furniture with plaster! The actual mold- 

 ing of the fish is followed in the same manner as described in the 

 forepart of this section. 



If the mold is to be transported some distance, it is advisable 

 to add sisal for strength. Dip a handful of this fiber in plaster 

 and place it over the first coat of plaster until the entire fish 

 and shelf are covered. An added precaution is the placement 

 of pipe along the sides and across the mold (Fig. 31). For 

 further details read Chapter 10. 



Molding at Home 



Although more care has to be exercised while working with 

 plaster at home or in the laboratory, there are many advantages 

 of convenience which cannot be had in the field. Fresh water 

 is at hand, the sun cannot dry out the specimen, and wind is not 

 present to blow sand over it. 



A frozen specimen must first be thawed out. If the fins are 

 dry, do not attempt to place them in position until they have 

 been soaked in water. Wrap wet cloths or wet paper towels 

 around the fins and the tail, or place the entire fish in water. 

 When the fins are soft, prepare the fish as previously described. 



If you have been able to bring home only the skin, proceed 

 as follows to build the body out to its former contours for mold- 

 ing. Fill the head and skin with ground gray asbestos which 

 has been mixed with water to a putty-like consistency. Sew the 

 skin together partiallv; then add or remove asbestos. Finish 



