Finish for an exterior door

[crokett™]

The door is walnut.  It will be on the north facing side of my house under a covered porch that is 6’x6’ so the door will see little if any direct sun.  Their is no storm door.   It is finished with Watco Danish Oil. Can I just use an exterior rated urethane for UV protection?

[fredhargis]

I wouldn't. Any product with urethane in it that is used outdoors will likely fail...probably fairly quickly. Urethanes just don't do well outside, UV is a big killer but the other elements are tough on it as well. That said, any clear coat outdoors will need maintenance over time no matter how robust they are. So te better choices (IMHO) would be a true marine varnish. Epifanes names seems to always come up, but there are several that are quite good. One I've used that has done well in my household setting is McCloskey's Man 'O War. None of these will have urethane resins. There are some water borne finishes as well, though I'm completely unfamiliar with them.

[jteneyck]

Fred, you're right about many urethanes but you are forgetting that Imron, about the most durable outdoor paint ever made, is a urethane.  And there is a whole class of exterior 2K polyurethanes available that nearly as durable as Imron.  There are even a few WB ones available these days, from ChemCraft IIRC, and others.  If the OP is comfortable with spraying and suiting up to avoid the hazardous catalysts used in these products then 2K poly would be a very durable choice.  

For us mortals I have used GF's Exterior 450, which also is an uncatalyzed urethane with a good UV package on an exterior door and have had no issues with it for 4 years.  It faces South but gets only a little sun and no direct weather.  It's easy to use but has a sort of cloudy appearance, not as attractive as many varnishes.  

Epifanes is nice stuff but best left for boats an exterior furniture IMO.  You have to apply 7 coats of the stuff, which takes at least a week, and it remains soft for a very long time.  It's not a very practical solution for an exterior door, although I know some people use it.

I don't know if it will be compatible with the Danish Oil already applied, but Osmo UV Protection Oil would be a product I'd strongly consider.  [/url]

[url=https://osmocolorusa.com/product/uv-protection-oil/]Link

John

[fredhargis]

I concede the 2k finishes are superior. to many other products...but I never suggest them (nor have I used any) because of the hazards involved. I've also not used GF exterior 450, which I will do in time, but it is an acrylic mix and while I don't know what part is urethane versus the acrylic, I'd bet there a lot more acrylic and just a small dollop of urethane. Not arguing with you at all, but at a consumer level, I'll still recommend skipping urethane finishes for outdoor use. I've never heard of Imron, guess I should read up about it.

[lift mechanic]

I used Bona Mega floor sealer over Minwax oil stain. 1 a 8' x 12' sliding garage door and a man door. This was over circular sawn dug fir flooring. The doors are not exposed to direct sun or weather. It has been 5 years and they are as the day I finished them. The Bona Mega is a water base product very easy to apply to a flat surface. I don't know how it would work in a vertical surface.

[crokett™]

Thanks for the suggestions x. I’ll look into them. The door will have all the finish applied while It is still horizontal.