Ultrathin sectioning

Ultrathin sectioning is not difficult as such, but it is fiddly and requires fine motor skills.

There are several steps

1. Trimming the block. In this step we remove excess resin and make the block face small enough for ultrathin sectioning. be careful with razor blades and do not cut yourself.
2. Inserting the sample in the microtome. Make sure to tighten the sample in the chuck and the chuck in the goniometer with the two red-handled allen keys.
3. Approaching the knife. The diamond knives used for ultrathin sectioning are both fragile and expensive. It is important to treat them with care to not chip the knife edge, knock the knife out of the holder, or knock your sample off the resin block. With the knife secured in the knife block and the block secured in the microtome, carefully move the knife forwards using the coarse and fine movement on the left, while rotating the hand wheel.
4. Filling the knife boat. Fill the knife boat with pure water, adding a few drops of ethanol to break the surface tension. Ethanol can also be used to "wet" the knife surface which is naturally hydrophobic.
5. Cutting manually. After trimming the sample face likely isn't mirror smooth. Using the older knife, cut 200 nm sections until the whole face is smooth, by rotating the handwheel backwards/clockwise. NEVER ROTATE THE HANDWHEEL FORWARDS.
6. Cutting automatically. Once you're happy with the sample face, you can cut sections to the thickness you need automatically. Put the good knife on the microtome and approach. Set the cutting window using the two buttons, then press CUT. Collect the ribbons as they come off.
7. Tidying. Rinse the knife boats out with isopropanol or ethanol (never acetone) and use a styrofoam stick to clean the knife edge.

Ultramicrotomy: The Art of Sectioning for TEM

This video shows the best example I've found for block trimming and knife approach. (Sound not required, it is music not explanation)