Troubleshooting Microtomy

PROBLEM CAUSES
Crooked or uneven ribbons Edges of knife and block are not parallel
The four sides of the block are not trimmed parallel
Wrinkled or compressed sections Blunt or dirty knife
Warm block or knife
Clearance angle too small
Thick and thin sections Loose knife or loose block
Clearance angle too small
Tissue or wax excessively hard
Areas of calcification present in tissue
Blunt knife
Sections adhere to block on upstroke of microtome Clearance angle too small
Blunt or dirty knife
Ribbons split vertically or scratch lines appear Small nicks or dirt on the knife edge
Clearance angle too large
Hard material embedded in the wax (grit, dirt, crystals, talc)
Hard material in the tissue (calcium, crystals, sutures)
Sections crumble or tear Tissue incompletely dehydrated
Tissue not cleared properly
Paraffin wax denatured from excessive heating
Wax has crystallized from slow cooling
Blunt knife
Wax too soft
Wax is contaminated with clearing agent or water
Section shows areas of varying thickness (‘washboard’ or ‘venetian blind’ effect, chatter) Loose knife or block
Clearance angle too large
Excessively hard tissue or wax
Sections will not ribbon Clearance angle too small or too large
Dull or dirty knife edge
Wax surface too cold
Section thickness setting too high
Sections roll up on cutting Blunt knife
Clearance angle too large
Section thickness setting too high
Sections disintegrate on water bath Water temperature too high, inadequate processing

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