Knife lines: Ribbon splitting lengthwise, knife lines (shown in the upper image) running along the length of sections (perpendicular to the blade)
- Tissue: Any tissue, particularly calcified tissue, and tissue with hair or bone
- Cause: Micro-calcifications in tissue, foreign materials in tissue, nicks in blade, dull or dirty blade, and impurities in paraffin
- Correction: Change blade, do not introduce tools to the edge of the blade, surface decalcified tissue, meltdown tissue with foreign objects and remove before re-embedding, or use different paraffin to embed tissue
"Parched earth," tears, separations, fissures: Cracks in tissue like a desert (shown in the lower image); tissue elements have separated and fractured.
- Tissue: Any tissue, particularly those that are bloody or fatty
- Cause: Poor fixation or processing, over-stretching sections, keeping sections on water bath too long, water bath too hot, or using cryo spray
- Correction: Increase fixation time, decrease dehydration time during processing, do not over-stretch sections, keep water bath within the temperature range, do not leave sections on the water for more than 10–15 seconds, manipulate sections gently, or use the freezing spray at a distance for only 1–2 seconds to prevent cracks in the tissue
Debris, floaters, epithelial cells: Artifacts that lay on top or underneath the tissue sections and around the sections on slides
- Tissue: Any tissue, especially bloody tissue
- Cause: Failure to clean water bath after each ribbon, water is contaminated with skin cells falling into the water, tissues dissolve or disperse in water and cells are being carried onto sections, tools are contaminated, and dirty/caked blade
- Correction: Change water at least daily, don’t lean over a water bath, use gloves, skim water surface with lint-free wipes after each ribbon, clean tools after each block, and change blades when they get caked with paraffin and tissue
Bubbles: Bubbles trapped under tissue, causing dark circular areas with torn edges
- Tissue: Any tissue, particularly brain
- Cause: Bubbles released from the base of the flotation bath or ribbon slapped on top of the water bath surface trap bubbles
- Correction: Remove bubbles from the bottom of the water bath before ribboning and place ribbons gently onto the water surface
