Fast Growth is Stronger (sometimes)

The Devil can quote scripture, after all. And monsters can say “please” and “thank you” same as any mother’s son.

Elizabeth Bear, Karen Memory

I noticed this piece of red oak and thought it would be a good opportunity to explain why fast growing wood is, in some cases, stronger than slow growing wood. You can see below the holes (more of a matrix really) that is seen in ring porous woods during early wood growth stage. This is during the spring of the year when the sap runs and the tree is growing quickly.  The size of this growth, ie the width, is pretty consistent year over year. Next as the starches in the roots run out the tree transitions to so called late wood this is the growth that is put on during the summer and early fall.  

Below you can clearly see years of good late wood growth and years of poor late wood growth.  The difference in strength thus becomes the ratio of early growth to late wood. In the lower part of the picture you can see the ratio is about 50 50 vs the upper part where it looks to me to be about 4 or 5 to 1. So the wood in the top of the picture is much stronger than the wood in the bottom. 

A couple points. Early wood and late wood are not to be confused with juvenile (sometimes called reaction) wood which is something else entirely.  

Second this does not apply to diffuse porous woods (like maple) which are stronger the slower they grow. 

So when you are looking at ash logs or oak for chairs be sure to look for faster growing trees. 

(There is no red oak where I live (Northern Maine) so this log came from central New Brunswick and if you zoom the below picture you can clearly see times of fast growth and for some reason two 5 to 8 year periods of very slow growth).