improving tension strength of woods with walnut oil

[lonbow]

I think that most of us know that different humidity levels change the properties of wood. Many woods tend to be brittle (weak in tension) when the climate is to dry. Wet woods on the other hand are very strong in tension.

One bowyer told me that he generally puts walnut oil onto the sapwood of his yew bows (walnut oil penetrates deep into the wood and dries very slowly). He thinks that it improves the tension strength of woods like high moisture.

Has anyone here also heard about this? Do you think this is true?

cheers, lonbow

[simk]

With similar thoughts I always oil the back of my bows before I start bending them.
But hey, its again one of those many things in bowmaking you will never be able to really proof. Its just what your guts talk to you 😁

[Badger]

   I have always believed this to be true but never bothered to try and prove it. I see it as just a good practice. I don't think anything penetrates wood all that deep though unless it enters at a ring line.

[Hamish]

In truth I have no idea if it works, or not. I remember one English bowyer recommended never oiling a bow because it made them go soft and limp. I think it was Hillary Greenland, referring specifically about yew, but using linseed oil, not walnut.

[jameswoodmot]

Realistically you will get very little penetration. Walnut oil will polymerise even if slowly and after a few coats will fill the wood and it will not penetrate any deeper. Though I’m sure cracks will start on the surface, so maybe it is just that first mm or so that needs the help.
Fairly easy to do bend test with enough pieces of timber to get a good sample.

The ash tool handles I make are soaked in hot raw linseed oil. It will polymerise at a similar rate to walnut and soaks in much deeper than applying cold. Good Ash doesn’t pick up a lot of oil but slow grown ash and things like beech suck it up and there is a noticeable increase in weigh. A splinter of oil soaked wood will behave differently to dry. Difficult to describe the difference.
I have little experience with yew but it doesn’t seem like a wood that will absorb much oil.
Too much walnut oil too quickly can go rancid before it has chance to polymerise.
I imagine oil will I’ll only increase tension strength when it is in liquid form, when it has polymerised I would imagine it will weaken the wood and/ or increase internal friction (hysteresis?)

[Jim Davis]

Oil such as boiled linseed oil makes a great finish that helps waterproof woo, but  woods are already 3 to 4 times stronger in tension than in compression. It is true that tension fractures are sudden and without warning, while compression failures are often preceded by the taking of  set/string follow.

Oil will not improve tension strength. I won't be back to argue about  this. If you doubt it, do  some research outside forums and social media.