How do you measure thickness?

[Kevin_r]

I am wondering on how do you get the thickness of cross sections for handheld microtome.

[mrsonchus]

Hi Kevin, sometimes in my rotary-microtome sections a cell-wall will have been flattened and therefore lie flat in the mount. It's and easy job just to measure it's width from there, which gives the thickness. It always surprises me just how accurate a rotary microtome is able to cut sections as per the setting.
It should be easy enough to apply the same idea to a hand-cut, just flatten a tiny area/piece of a hand-section and look for some that are lying flat that would have sectioned vertically when hand-cutting.

[Hobbyst46]

If you can mount the section flat on a slide, and focus on its top and bottom, respectively, record the focus knob position at each point, and note the height difference from the number of focus knob turns and the delta per turn, you easily know the achieved thickness of the slice.
On my microscope for example, 2 micrometers per scale mark and 50 marks per knob turn. The range of movement of the fine focus is 2mm. Covers it all.

[MicroBob]

Hi Kevin,
when I cut sections and advance e.g. 40µ per section, get a section with each cut and all sections look the same - they have a thickness of 40µ, precise enough.
What is the background of your question?

Bob

[Kevin_r]

I do appreciate your replies.
I’ll definitely try using the focus adjust knobs.
...
For context, I got this microtome (see picture) without any documentation to what numbers meant. It works great on making equally thin sections, but I would like to verify the thickness.

[PeteM]

You can get an idea of how it's graduated by noting how many graduations per turn (50) and the setting it flush and then back it off, say, twenty turns and measuring the depth with something like a digital caliper. Divide by 1000 (50 x 20) and you'll have your answer.

[MicroBob]

Hi Kevin,
if this were a metric hand microtome it would advance 0,5mm per turn.
The screw cap at the bottom only advances the piston, it doesn't retract it. So to carry out Pete's test it would be best to start in a low position and turn the piston upwards.

The hand microtomes available today often have a very loose fit between cylinder and piston. This problem can be adressed by applying a very stiff grease. The blade also tends to lift the piston, especially with specimen with a lot of lignified firbes. This leads to uneven sections and lots of trouble. The stiff grease solves this problem too. I use over 50 year old military rust protection grease for this application.

Here in Germany we use these hand microtomes with blade holders. This saves the edge as it doesn't scrape over the table suface. The hand microtome in much easier to use when attatched with a make shift holder to the desk.

Bob