|I custom engrave wood signs made from aromatic eastern red cedar boards with "live edge". I have always sprayed the wood with Minwax spar polyurethane clear satin finish...but it darkens the red and white parts of the wood sign. Do I need to use a polyurethane coating on the wood to preserve it for outdoor wood signs? is only the red "heartwood" rot resistant? is there another clear polyurethane spray that will not darken the wood?|
|I have rough cut eastern red cedar for siding, I use Sikkens on the house, pretty much everything you use on it will make it darker, Sikkens now has a "clear" that will work, but there will be a slight darkening of the wood. Rough cut is also rot resistant.|
|by "rough cut" I assume you mean not sanded? I have experimented with the wood by making it look "old" by using steel wool soaked in vinegar to turn it gray like oxidized wood. It turns a light to dark gray but when I spray it with polyurethane coating it gets very dark, almost brown. I did not sand the wood so it has a as natural a look as possible. Will that decay faster outdoors? it will be near a beach in Florida.|
|Any clear finish is going to darken wood.
If wood isn't going to be touching ground, you need not worry about rot. Sun and especially ocean air is going to eat, bleach, and wear wood wood really fast.
Your finish, even if marine grade, will be flaking and mostly gone in a year.
What kind of look you looking for ?
They make all different, kinds, and colors of stains these days. I'm sure you can find one for your needs.