Defects 



PARAFFIN SECTIONS 



Table 1 — {Continued) 



121 



Fig. 73. Sections alternately thick and 

 thin, usually with compression of thin 

 sections. 



Possible Causes 



1. Block, or wax holding hlock to 

 holder, still warm from mounting 



2. Block, or wax holding block to 

 holder, cracked or loose 



3. Knife loose 



4. Knife cracked 



5. Microtome faulty 



Remedies 



1. Cool block and holder to room 

 temperature 



2. Check all holding screws, Remove 

 block from holder and holder from 

 microtome. Melt wax off holder 

 and make sure holder is dry. Re- 

 coat holder and remount block. 

 Cool to room tcMiiperature 



3. Release all holding screws and 

 check for dirt, grit, or soft wax. 

 Check knife carriage for wax chips 

 on bearing 



4. Throw knife awav 



Fig. 74. Sections bulge in middle. 



Possible Causes 



1 . Wax cool in center, warm on outside 



2. Only sharp portion of knife is that 

 which cuts center of block 



3. Object impregnated with hard wax 

 and embedded in soft, or some 

 clearing agent remains in object 



Remedies 



1. Let block adjust to room temper- 

 ature. This is the frequent result of 

 cooling blocks in ice water 



2. Try another portion of knife-edge 

 or resharpen knife 



3. Re-embed object 



5. Return 



microtome to maker fur 



overhaul 



