Ribbon does not form

Crooked ribbons

Sections are irregular, skipped, thick or thin

Sections are compressed, wrinkled or jammed together

Sections crumble, specimen may tear out

Split ribbon or lengthwise scratches in ribbon

Knife rings on upstroke and sections are scratched

Sections lifted from knife on upstroke

Sections stick to knife & Sections fall out of matrix or show compression different from embedding medium frame

Other

Undulations in the surface of the section

Sections fly and stick to parts of microtome or other nearby objects

Knife does not hold its edge