Once the tissue has been oriented, a few quick steps will finish the process.
Step Four: Complete the paraffin block
Add a small amount of molten paraffin to completely cover the grooves or openings in the cassette's plastic. This will ensure that the specimen and cassette bottom will harden together into a secure block. As you replace the cassette, avoid air bubbles from being trapped below it. Do this by tipping the mold slightly and pushing the trapped air out. Start at one corner of the mold and press any air outward as you replace the cassette.
Step Five: Harden
Move the completed block to the large cold plate to harden. Allow the block to completely cool and harden on the cold plate before attempting to remove it from the base mold. When completely cooled, the block's paraffin will usually appear opaque and white.
Step Six: Scrape
Neatly scrape excess paraffin from the edges of the block to ensure a secure fit into the microtome's block holder. Take care not to scrape off or damage the cassette ID.
Step Seven: Inspect
Before submitting the block for microtomy, check for obvious defects, such as cracks or air bubbles.
