Making Sections 



Table 2 

 Defects Appearing while Sections Are Being Cut 



155 



Defect 



Possible causes 



Remedies 



1. Edges of block not parallel 



2. Knife not uniformly sharp, 

 causing more compression 

 on one side of block than 

 other 



3. One side of block warmer 

 than other 



Fig. 118. Ribbon curved. 



1. Trim block 



2. Try another portion of 

 knife-edge or resharpen 

 knife 



3. Allow block to cool. Check 

 possible causes of heating 

 or cooling, such as lamps 

 or drafts 



1. Knife blunt 



Fig. 119. 

 pressed. 



Sections com- 



2. Wax too soft at room tem- 

 perature for sections of 

 thickness required 



3. Wax warmer than room 

 temperature 



1. Try another portion of 

 knife-edge or resharpen 

 knife. Compression often 

 occurs through a rounded 

 cutting facet ( see Fig. 107) 

 produced by overstropping 



2. Reembed in suitable wax 

 or cut thicker sections. 

 Cooling block is rarely suc- 

 cessful 



3. Cool block to room tem- 

 perature 



Fig. 120. Sections alter- 

 nately thick and thin 

 usually with compression 

 of thin sections. 



1. Block or wax holding block 

 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 



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. 

 Recoat holder and remount 

 block. Cool to room tem- 

 perature 



3. Release all holding screws 

 and check for dirt, grit, or 

 soft wax. Check knife car- 

 riage for wax chips on 

 bearing 



4. Throw knife away 



5. Return microtome to maker 

 for overhauling 



