In article , "Martin" wrote:

I've seen in several bonsai books and on the net the use of training boxes
for larger specimens of Yamadori etc. I was wondering what would be the best
timber to use for say a 5 year stint as a training box. My main concern
being timber rot and it's effects on the roots of my plants.

I knocked up one box out of dressed (smooth sanded) pine planks I had laying
around and sealed them with clear varnish but am still somewhat concerned
about the planks rotting.

Any tips in regards would be greatly appreciated.

Martin

I'd give it a few coats of marine varnish. If it's good enough for boats,
it ought to protect a planter from rot. And I'd wait at least a week
before using it, just to make sure the varnish is fully cured.