faults observed during sectionin cutting

• REASON: Sections expand or disintegrate on water bath

  • Poor impregnation of tissue
  • Water temperature too high in flotation bath
• REMEDY: Sections expand or disintegrate on water bath

  • Re-process tissue
  • Turn down the temperature of the flotation bath
• REASON: Sections roll into a coil instead of remaining flat on knife edge

  • Blade dull
  • Rake angle too small
  • Section too thick
• REMEDY: Sections roll into a coil instead of remaining flat on knife edge

  • Use a new blade
  • Reduce blade tilt if clearance angle is excessive
  • Reduce section thickness
• REASON: Grooved, Scored, smeared and deformed sections

  • Dull knife /blade edge
  • Too warm room
• REMEDY: Grooved, Scored, smeared and deformed sections

  • Re-sharpen the knife/blade or move the existing blade to an unused surface or replace it with a new one
  • Cool/change the temperature of the room or cool the block in ice water
• REASON: Sections fail to form ribbons

  • Surfaces and edges of the block are not parallel
  • Horizontal surface of the block is not parallel to the knife
  • Paraffin wax is too hard
  • Knife is tilted too much
  • Sections are too thick
  • Knife is dull
• REMEDY: Sections fail to form ribbons

  • Re-trim the block
  • Re-adjust and re-orient the block
  • Coat horizontal edges of the block with wax of lower melting point
  • Reduce the tilt
  • Re-adjust thickness of the section
  • Hone and strop
• REASON : Sections roll up on cutting so that they adhere and get broken gainst the knife edge

  • Knife is blunt
  • Tilt of knife is too great
  • Knife edge is dirty
• REMEDY: Sections roll up on cutting so that they adhere and get broken against the knife edge

  • Sharpen the knife
  • Reduce the tilt
  • Clean the knife edge
• REASON: Ribbon is curved, crooked or uneven instead of straight

  • Blunt of dull spot on the knife, producing an irregular knife edge
  • Edges of the block are not parallel but round or wedge shape
  • Knife is not parallel to the block
  • Paraffin is impure
• REMEDY: Ribbon is curved, crooked or uneven instead of straight

  • Adjust the knife so that knife edge will present a uniformly sharp edge to the block or sharpen
  • Re-trim the block
  • Readjust knife and block
  • Repeat impregnation using pure wax
• REASON : Sections are compressed wrinkled or jammed

  • Knife is blunt or dull
  • Paraffin block is warm and soft
  • Knife edge is coated with paraffin
  • Sections are too thin
  • Microtome set screw is loose
  • Tilt of knife is too vertical
  • Too rapid cutting
  • Too warm room
  • Unparallel block edges
• REMEDY: Sections are compressed wrinkled or jammed

  • Re-sharpen the knife
  • Cool the block on ice water until firm
  • Clean the knife edge
  • Re-adjust thickness of section
  • Tighten screw
  • Reduce the tilt
  • Decrease cutting speed for every thin section
  • Cool/change the room temperature or cool the block in ice water
  • Trim the block edges until they are parallel
• REASON : Sections are squashed (width of each section is less than that of block)


  Bevel of knife is lost due to incorrect sharpening
• REMEDY: Sections are squashed (width of each section is less than that of block


  Re-sharpen using a knife back or automatic knife sharpener
• REASON: A hole is formed in the section

  • Bubble or dirt formed in the embedding medium
  • Hard spot in tissue due to calcium
  • Excessive dehydration or improperly processed tissue
• REMEDY: A hole is formed in the section

  • Re-embed in freshly filtered wax if necessary
  • Once embedded in paraffin wax, decalcification is impractical; use a base sledge microtome with a wedge knife
  • Expose the tissue, then soak the block in ice water or with a piece of cotton before sectioning
• REASONS: Sections of unequal thickness are produced

  • Tilt of knife is too great or bevel is not cleared hence object is compressed against the knife edge
  • Clamp set screw on knife or blockholder is loose
  • Blocks are too large
  • Blocks are too hard
• REMEDY: Sections of unequal thickness are produced

  • Reduce the tilt
  • Tighten the screw
  • Cut blocks into smaller fragments
  • Soften the blocks in detergent or phenol
• REASONS: Sections adhere to the knife or other parts of the microtome

  • Static electricity due to low atmospheric humidity
  • Knife edge is dirty
  • Knife edge is dull
  • Tilt of knife is too great
• REMEDY: Sections adhere to the knife or other parts of the microtome

  • Breathe out or blow gently on the block and knife to breakup static electricity , or boil water in the room to increase humidity
  • Clean knife edge
  • Sharpen the knife
  • Reduce tilt
• REASONS: Ribbon is split or lengthwise vertical scratches are seen on sections

  • Nicks or damage on the knife edge
  • Dirty embedding
  • Knife edge is dirty
  • Tilt of knife is too great
• REASONS: Sections are lifted from the knife on the upstrokes

  • Knife tilt is too great
  • Knife is dull
  • Paraffin is too soft or room temperature is warm
• REMEDY: Sections are lifted from the knife on the upstrokes

  • Reduce the tilt
  • Sharpen the knife
  • Cool paraffin wax in ice water
• REASONS: Resistance is felt on the lower part of the section during cutting


  Tilt of knife is too small, paraffin block is therefore compressed against the base of the knife towards the end of stroke
• REMEDY: Resistance is felt on the lower part of the section during cutting


  Increase the tilt
• REASONS: Horizontal or parallel lines or furrows across the section (chatters) are seen, forming thin and thick zones

  • Knife edge vibrates due to hardness of tissue
  • Tilt of knife is too great
  • Overhydration or lack of moisture in tissue
  • Use of dull knife/blade
  • Cutting too quickly
• REMEDY: Horizontal or parallel lines or furrows across the section (chatters) are seen, forming thin and thick zones

  • Treat with phenol during processing or collodionize
  • Reduce tilt
  • Restore moisture of tissue by letting the block stand and soaking it briefly in ice water or by placing it face down on an ice tray
  • Resharpen the knife/blade
  • Decrease cutting speed
• REASONS: Section cut is sometimes thin sometimes thick

  • Knife is blunt
  • Knife is not clamped properly
  • Tilt of knife is too great
  • Knife or block holder is loose
  • Knife tilt is too small that block is compressed by bevel and section is not cut
• REMEDY: Section cut is sometimes thin sometimes thick

  • Sharpen the knife
  • Adjust the knife
  • Reduce tilt
  • Tighten adjusting and locking screw
  • Increase the tilt
• REASONS: Knife makes a hard metallic scrapping or ringing sound on backstroke, when section is cut

  • Tilt of knife is too slanted or too big
  • Tissue is too hard
  • Knife blade is too thin
• REMEDY: Knife makes a hard metallic scrapping or ringing sound on backstroke, when section is cut

  • Readjust the angulation of the knife
  • Take fresh block treated with phenol during processing
  • Change the knife
• REASONS: Frozen tissue crumbles and comes off the block holder when cut


  Freezing is not adequate
• REMEDY: Frozen tissue crumbles and comes off the block holder when cut


  Refreeze the tissue block
• REASON: Frozen tissue chips into fragments when cut


  Tissue is frozen too hard
• remedy: Frozen tissue chips into fragments when cut

  • Warm the tissue with the fingers
• REASONS: Pleated, folded and crooked ribbons


  Imperfections in the blade edge, i.e. the horizontal edges are not parallel or the lower block edge is not parallel to the knife edge when sectioning
• REMEDY: Pleated, folded and crooked ribbons

  • Trim the block parallel to the other edge or re-embed them in molds so that the edge of blocks is parallel to the knife edge
  • Try another part of the knife edge