Mad Science for Exterior Finish

bmyyou | Posted in Finishing on October 11, 2006 05:18am

What would happen if I coated cypress outdoor wood with an exterior gel stain and sealed it with Thompson’s water seal? Would it protect the wood from UV damage or would the color fade and the wood grey anyway?

Thanks,

Brian

Replies

SteveSchoene | Oct 11, 2006 05:29am | #1
It would be grey in a few months if the piece were in the sun. Thompson's WaterSeal doesn't have a terribly good reputation, and the gel stain, unless just painted on so as to be an opaque finish wouldn't contribute much of anything.

Cypress left to grey is an elegant look. Any clear or nearly clear finish will require constant maintenance. A high quality oil based enamel paint in a light color would hold up the best.

If you are a glutton for punishment you could finish the cypress as if it were marine brightwork. To do this you would first apply a couple of coats of low viscosity epoxy, such as that from Smith & Co. Then, paying particular attention to the proper timing after the epoxy has been applied you would begin to apply approximately 6 coats of high quality marine spar varnish. There are three acceptable brands. Epifanes Gloss, Interlux Schooner, and Pettitt Captain's. You would then need to be sure to touch up any dings promptly and to scuff sand and add another coat about every year or so, depending on how far south you are and how much sun the chair would get.

Edited 10/10/2006 10:33 pm ET by SteveSchoene