what is the best varnish

[Robertastro]

I am looking for the best varnish for exterior plywood construction for a tear drop trailer.... I put polyurthane and it is peeling off.

[Craig McCormick]

We refinish a lot of expensive entry doors on high end homes and we use a product called Isolante. Not cheap though. About $150 per door for the base and top coats including all the proprietary thinners. No you will not find this at Home Depot, Lowe's or the likes. I buy it at a local store that specializes in wood finishes.

AZCRAIG