PRESERVATION OF SPECIMENS IN PLASTICS 



17 



used over the specimen itself because of the likelihood of crushing or 

 bruising it. 



In cases where the preserving fluid has become partially hardened as 

 the result of drying out while standing, it should be remoistened, either 

 by placing the layout in a humidifying chamber for 20 to 30 minutes or 

 by laying wet paper pads on it for a similar length of time. 



If the cover film tends to curl or wrinkle at the edges so that it may 



Figure 3. — When the treated specimen has been laid out on the plastic sheet and 

 covered with a cellulose acetate film, the excess of preserving fluid should be forced 

 out with a plastic squeegee (A) or a rubber roller (B). 



admit air to the specimen while being worked over, it can usually be 

 held in place by means of heavy glass or metal strips one-half to one 

 inch wide and of suitable length to cover the marginal area. In case 

 holes that admit air to the specimen develop in the cover film during 

 the working over, they can usually be patched with Scotch cellulose 

 tape; but in the event the holes are too large to patch, the punctured 

 cover film should be replaced with a new one. 



