| Question | Answer |
| Irregular or skipped sections may be caused by: | Too little/much blade tilt,
poorly adjusted chuck,
cutting too fast or at inconsistent speeds,
old or out of adjustment microtome,
loose screws/parts |
| Crooked ribbons may be caused by: | Blocks not trimmed parallel on horizontal sides,
irregular knife edge,
uneven block temp |
| Sections sticking to knife may be caused by: | Dirty knife - clean w/ xylene,
knife angle too small,
dull knife |
| Smeared/deformed sections may be caused by: | Dull knife |
| Washboarding/undulations in section may be caused by: | Block not clamped tightly,
too much knife tilt,
loose screws/parts,
old microtome,
under/overfilled block not sitting properly,
often happens w/ hard tissues (e.g. uterus) |
| Ribbon may not form because: | Cold room - warm knife slightly,
too much knife angle,
too thick sections,
dull knife |
| Sections compressed, wrinkled, or jammed together may be caused by: | Dull knife,
paraffin build-up on blade,
too little knife tilt,
cutting too fast,
warm room,
warm block |
| Knife rings on upstroke & sections are scratched | Knife angle too great > decr. angle
Material too hard > soak in water to soften |
| Sections may be lifted from knife on upstroke because: | Too little knife angle,
dull knife,
warm room - cool block,
soft paraffin |
| Knife may not hold edge because: | Knife angle is too severe |
| Scratches or splits in ribbon may be caused by: | Defect in block (e.g. calcium deposit),
defect in knife |
| Fragmented or torn sections may be caused by: | Poor processing or fixation,
too hot water bath,
treat ribbon more gently |
| Sections flying due to static may be helped by: | Breathing on section/blade,
humidifer in room,
dryer sheet behind blade |
| Chatter may be caused by: | Dry, over-processed tissue,
too much knife tilt,
cutting too fast,
block holder shaft over-extended - vibration |
| Holes in section may be caused by: | Facing block too roughly, tears tissue,
can try to face further & smooth |
| Parched earth artifact caused by: | Too hot bath,
using cryo spray to cool blocks,
facing too roughly, dry sections |
| Wrinkles in section may be caused by: | Not laying ribbon on bath carefully,
bath not warm enough |
| Prevent skin cells in sections by: | Wearing gloves,
not sticking fingers in bath |
| Prevent cross-contamination by: | Cleaning tools between blocks,
cleaning bath between blocks |
| To help keep sections on slide may use: | Slides coated w/ poly L lysine, aminoalkylsilane, or albumin,
(may get background staining artifact),
charged/plus slides |
