⑦ Paraffin impregnation

Impregnate the tissue with paraffin to make it hard enough to thinly slice.

The paraffin used for this process

※ Paraffin with a higher melting point is harder. Such paraffin can be thinly sliced; however, blocks of it become brittle. Thus, mixing recycled paraffin with hard paraffin increases block flexibility.

Hard paraffin (melting point, 56 − 58 °C) Recycled paraffin
Hard and recycled paraffin will always melt in a paraffin wax melter set to 60 °C.
Melting furnace set to 60 °C
Equal quantities of hard and recycled paraffin are poured into a melting furnace set to 60 °C.


  • Prepare paraffin baths I − IV by melting the paraffin and pouring it into four wide-mouthed containers and placing it into a wax melter set to 60 °C. A lid is not required.
  • Use filter paper to wipe the tissue slice taken from the chloroform bath and place it in paraffin bath I.
    Then successively place the tissue into paraffin baths II, III, and IV.
  • After placing the tissue into paraffin bath III, perform decompression with a vacuum paraffin embedding device for approximately 20 minutes to an hour.
    Following this, place the tissue into bath IV.
  • The intermediate solvent in the tissue is removed through the decompression process.

Guide for paraffin impregnation time

Paraffin impregnation step

Solution used for impregnationTissue sizes
Paraffin Ⅰ
Paraffin Ⅱ
Paraffin Ⅲ
Paraffin Ⅳ

Exchanging the paraffin solution