Faults & Remedies PDF

FAULTS REASON REMEDY Surfaces and edges of the block are not Re-trim the block parallel Horizontal surface of the block is not Re-adjust and re-orie...

FAULTS REASON REMEDY Surfaces and edges of the block are not Re-trim the block parallel Horizontal surface of the block is not Re-adjust and re-orient the block parallel to the knife SECTIONS FAILS TO FORM Paraffin wax is too hard Coat horizontal edge of the block RIBBON with wax of lower melting point Knife is tilted too much Reduce the tilt Sections are too thick Re-adjust the thickness of the sections Knife is dull Hone and strop SECTIONS ROLL UP ON CUTTING Knife is blunt Sharpen the knife SO THAT THEY ADHERE AND GET Tilt of the knife is too great Reduce the tilt BROKEN AGAINST THE KNIFE Knife edge is dirty Clean the knife edge; throw id EDGE disposable Blunt or dull spot on the knife producing Adjust the knife so that knife edge an irregular knife edge will present a uniformly sharp edge RIBBON IS CURVED, CROOKED to the block; or sharpen OR UNEVEN INSTEAD OF Edges of the block are not parallel but Re-trim the block STRAIGHT round or wedge-shaped Knife is not parallel to the block Re-adjust the knife and the block Paraffin is impure Repeat impregnation using pure wax Knife is blunt or dull Re-sharpen the knife Paraffin block is warm and soft Cool the block on ice water until SECTIONS ARE COMPRESSED, firm WRINKLED OR JAMMED Knife edge is coated with paraffin Clean the knife edge Sections are too thin Readjust the thickness of section Microtome set screw is loose Tighten the screw Tilt of knife is too vertical Reduce the tilt SECTIONS ARE SQUASHED Bevel of knife is lost due to incorrect Re-sharpen, using the knife back or (WIDTH OF EACH SECTION LESS sharpening automatic knife sharpener THAN THAT OF BLOCK) Bubble or dirt formed in the embedding Re-embed in a freshly filtered wax if medium necessary A HOLE IS FORMED IN THE Hard spot in tissue possibly to calcium Once embedded in paraffin wax, SECTION decalcification is impractical; use a base ledge microtome with wedge knife  Tilt of the knife is too great or bevel is not Reduce tilt cleared, hence object is compressed against the knife edge SECTIONS OF UNEQUAL Clamp set screw on knife or block holder Tighten the screw THICKNESS ARE PRODUCED is loose Blocks are too large Cut blocks into smaller fragment Blocks are too hard Soften blocks in detergent or phenol Static electricity due to low atmospheric Breath out or blow gently on the humidity block and knife to break up static SECTIONS ADHERE TO THE KNIFE electricity, or boil water in the room OR OTHER PARTS OF THE to increase humidity MACHINE Knife edge is dirty Clean the knife edge Knife edge is dull Sharpen the knife Knife tilt is too great Reduce the tilt RIBBON IS SPLIT OR Nicks or damage on the knife edge Sharpen knife LENGTHWISE VERTICAL Dirty embedding medium Re-embed in filtered wax SCRATCHES ARE SEEN ON Knife edge is dirty Clean knife edge with xylene SECTIONS Tilt of the knife is too great Reduce tilt Knife tilt is too great Reduce the tilt SECTIONS ARE TILTED FROM THE Knife is dull Sharpen the knife KNIFE ON UPSTROKES Paraffin is too soft or room temperature is Cool paraffin wax in ice water warm Tilt of the knife is insufficient; paraffin RESISTANCE IS FELT ON THE block is therefore compressed against the LOWER PART OF THE SECTION Increase the tilt base of the knife towards the end of the DURING CUTTING stroke HORIZONTAL OF PARALLEL LINES Tilt of the knife is too great Reduce the tilt FURROWS ACROSS THE SECTION Knife edge vibrates due to hardness of the Treat with phenol during processing (CHATTERS) ARE SEEN, FORMING tissue or collodionize THIN AND THICK ZONES Knife is blunt Sharpen the knife Knife is not clamped properly Adjust the knife SECTION CUT IS SOMETIMES Tilt of the knife is too great Reduce the tilt THIN, SOMETIME THICK Knife or block holder is loose Tighten adjusting and locking screws KNIFE MAKES A HARD METALLIC Tilt of the knife is too slanted or too big Readjust the angulation of the knife SCRAPING OR RINGING SOUND Tissue is too hard Take fresh block treated with ON BACKSTOKE, WHEN SECTION phenol during processing IS CUT Knife blade is too thin Change the knife FROZEN TISSUE CRUMBIES AND COMES OFF THE BLOCK HOLDER Freezing is not adequate Refreeze the tissue block` WHEN CUT FROZEN TISSUE CHIPS INTO Tissue is frozen too hard Warm the tissue with the fingers FARGMENTS WHEN CUT  Prolonged fixation Prolonged dehydration Tissue may be softened by soaking Prolonged clearing BRITTLE OR HARD TISSUE in a small dish or bowl containing Prolonged paraffin infiltration detergent, phenol or Molliflex Overheated paraffin oven Drying out of tissue before actual fixation