Does wood finish itself cause wood to expand? Shella/varnish

[custard]

So what was that you were claiming again custard?

Exactly what this chart demonstrates, that trying to stabilise wood with a surface finish is a fool's errand.

 

[Jacob]

The truth is in the middle: any finish will stabilise humidity to some extent i.e. reduce the highs and low in a variable environment, but in a stable environment no finish will give permanent protection, short of gold leaf or similar.

 

[Woody2Shoes]

Surely in the case of this flat walnut board, or any other similar board, the great majority of the moisture goes into/out-of the end-grain anyway? (I'm not calling anyone Shirley, honest!).