Varnishing Question

[cajoledcruiser]

My husband is wondering if it is advisable to varnish the back side of trim, particularly large pieces. I tend to think if it looks fine after 25 years, why bother, but thought I'd get some opinions.
Thanks!
Linda

[FlyingCloud1937]

It's good to backside seal open grain wood, as moisture can migrate through and cause lifting of the front side varnish.

Teak, no worries, as the wood is so dense with its own oil, moisture can't migrate.

Lloyd

Originally Posted by cajoledcruiser

My husband is wondering if it is advisable to varnish the back side of trim, particularly large pieces. I tend to think if it looks fine after 25 years, why bother, but thought I'd get some opinions.
Thanks!
Linda

[Chenega]

In working as a boat wright carpenter for 25 years, we always seal the back side of exterior wood - teak included - to prevent moisture from wicking into the wood and causing the varnish to lift. This is especially true in climates of freeze and thaw. Rather then sealing with varnish, use epoxy (back sides only) prior to installation. Extends the life of varnish (or paint) dramatically...

[Nicholson58]

I also slop a seal coat on all around on new wood.