Note: this is a slightly tweaked encore (think summer re-run) of a 2010 Wood Spin article

 

At various points in my ten years of woodturning experience, I have encountered the following statements:

Emmett

this wood is full of sand and will dull your saw and tools quickly

since that tree was growing in sandy soil, it will be filled with sand

trees suck up sand

osage orange is full of sand and that is why it is so hard to cut

Plus, at least a dozen variations on these statements, all authoritatively stating that wood which is hard to cut, and which quickly dulls tools, is wood with a high sand or “silica” content.  Please recognize, on the front end, that sand is not synonymous with silica.

 

01 Sand from Gobi Desert thumb

Is this true? Or, are we dealing with old woodturners tales and mixed up correlations?  I recall one famous scientist who believed, as a child, that tree limbs whipping around caused the wind to blow.  It was not until he was ten years old, in the middle of the ocean, and encountering a lot of wind that he realized that his correlation was amiss.   But it is certainly true that some woods are much more difficult to cut than others and that some woods will dull tools quickly.

02 Osage Orange Bowl thumb

 

In attempting to sort out the issue of sand in wood, I have dug around in all sorts of chemical and botanical sources, including contact with the person perhaps best qualified to provide the science needed to answer the question -- Rob Wallace, Ph.D., botanist and accomplished woodturner, Iowa State University.  Via e-mail, Rob was kind enough to provide answers to many of my questions and to admit that he does not have all of the answers to this intriguing quest.

 

Let me provide a list of facts, some of which may raise more questions than they answer:

1. Silicon Dioxide (which is quartz, which in small granules is termed sand) is essentially insoluble in water or in the aqueous liquid we refer to as sap. If sand was water soluble, we would not have any beaches.

2. Sand granules are too large (and too insoluble) to move up a tree via the transport systems which exist in trees. This does not happen. There is no sand in a tree except that pressed into the wood by direct contact of the wood surface with sand.

3. If sand were in a particular wood, it should be visible to the naked eye when a fresh cut is made in that wood.  Certainly visible with a simple magnifying glass.  It is not there.

4. It is true that sand/quartz is a hard substance: 7 on the Mohs Hardness Scale where 1 is talc and 10 is diamond.  Quartz will quickly dull saw blades and tool edges. No disagreement here.

5. Sand may be imbedded in logs which have rested on sandy soil.

03 Harvesting Dead Limbs thumb

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Monday the 29th. Thanks for visiting Woodturners Unlimited.