An Introduction to the identification of wood from thin sections (with applications to fossil wood found in Quaternary deposits) **
By: R.J. Mott
Emeritus, Geological Survey of Canada
Making sections & Slides
There will be a demonstration of the procedure for making thin sections in class, and you can try to make a few yourselves.
1.Cut off a block of the wood of approximately 1 cm3.
Take a portion from the best part of the wood available. Try to avoid the branches, etc. When cutting the section from the disk, get as right an angle as possible. If you have a choice, use the outside of the section.
2. Boil the block of wood in water.
This softens the wood to make the thin sections easier to cut. Boil the wood until it sinks.
Fossil wood: keep it wet until you make the section; don't let it dry. Once fossil wood dries, it shrinks and the cells collapse. You usually don't need to boil fossil wood. Some woods can be soaked in KOH to soften.
3. Clamp the wood in the microtome.
The wood specimen should protrude only 1/2 cm.
4. Start cutting the sections.
5. Remove the sections from the water with tweezers.
Take a few and drop in stain. Let them sit for a while. Note: stain modern wood, but fossil doesn't need stain. Then put them back in the water (they should be blue) to remove some stain, put a drop of acid in the water.
6. Now run the sections through the washes.
7. Place the sections on a slide with some permount.
Place a drop of permount on the slide. Taking the section from the xylene, touch it on some paper, but don't draw off all the xylene. Orient the sections properly, place a drop of permount on top, and then the cover slip. Make sure to put the cover slip on before the xylene dries, or you will get bubbles. Place the slides, with permount and cover slip, on a hotplate (50 o C) and leave overnight. Add a small weight on the coverslip. This prevents the sections from curling and lifting the coverslip.
8. Scrape off excess permount, and clean with xylene. Label the slides.
**This page describes the method used to make thin sections of wood. It is based on my notes taken during a a short course on Wood Identification offered at the University of Ottawa, Department of Geography, June 1998. The methodology is that used by R. Mott, of the Geological Survey of Canada, and this page is taken from the short course. K. Gajewski.
© University of Ottawa
If you are looking for additional information, please contact us.
Technical questions or comments about this site? Last updated: 2009.11.23