Finish for exterior door, is Varathane interior finish OK?

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Forum topic by LarsCA posted 12-28-2015 07:21 PM 782 views 0 times favorited 14 replies Add to Favorites Watch
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16 posts in 2652 days

12-28-2015 07:21 PM

Topic tags/keywords: exterior varathane finish door mahogany

We picked up our new exterior door a couple of weeks ago and then had a cabinet maker (who makes furniture for the company I work for) cut it down to size, removing a scant 1/2 inch from each side so that the door is now 35” wide, like my existing door. Then this week-end we started finishing the door, first using an inferior product from Lowe’s (where I do not normally shop) that someone who works there recommended to me. I went to Lowe’s because I expected to buy Cabot stain and finish, but I learned that those are no longer sold in California, and I would have to go to Nevada or Arizona to buy it, and I do not want to buy something that toxic anyway. So the guy at Lowe’s sold me a product that is supposed to be a stain and finish in one step, and he told me that it was translucent and would allow the grain of the wood to show through – it wasn’t and it didn’t.

Next we went to Home Depot to buy finish remover and a separate wood stain and finish and ended up with Varathane oil-based satin finish and Cabernet stain. I bought the interior finish instead of the exterior because of reviews that I had read, and I felt that it would be sufficient for my door. The door is set back about six feet and is protected by an overhang of the roof, and it faces northeast and I’ve never seen it get direct sun. It also never gets any rain either, and we also have new gutters. In addition, we do not get extremes of temperatures, and so I think this finish should be okay for our door. Anyway, if it needs any touch up, we will be able to do that ourselves, since we are in the process of finishing the door ourselves.

Do you think I should be concerned about using an interior polyurethane finish on my door? If so, what would be the reason? Would teak oil be better or more appropriate? We used that for our outdoor teak dining table, and it required touch up about once a year or so. I have photos but am not sure how to post them. The door is made of mahogany.

14 replies so far

View sawdustdad's profile


117 posts in 308 days

#1 posted 12-30-2015 12:49 AM

I would not use an interior finish on the exterior side of the door. The traditional finish for the exterior side of a mahogany door would be a spar varnish. If it were mine, I’d be looking at a marine finish such as Cetol or a marine varnish, both durable exterior finishes for solid wood. Sikkens Cetol is translucent and is easy to repair/refresh if needed in the future. Any of the various varnishes are more durable initially but more difficult to repair.

Lots of choices at your local marine supply house or online at places like this

-- Murphy's Carpentry Corollary #3: Any board cut to length has a 50% probability of being too short.

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Fred Hargis

3848 posts in 1916 days

#2 posted 12-30-2015 03:02 PM

That would be a huge mistake, as wpould anything with urethane resins (They don’t do well in an UV environment). The true marine spar varnishes is what you want…another choice would be untinted paint. In CA you may have trouble finding anything oil based, so a good waterborne that has UV inhibitors would be GF High performance. A note on that paint article, it references oil based paint but many of the waterborne formulas (like SW A-100 exterior) dry clear and have the desirable properties as well.

-- Our village hasn't lost it's idiot, he was elected to congress.

View johnstoneb's profile


2106 posts in 1596 days

#3 posted 12-30-2015 03:13 PM

Given the location and orientation of your door you are probably going to be good with the chosen finish. If it doesn’t You can always refinish with an exterior product down the road.

-- Bruce, Boise, ID

View dbray45's profile


3147 posts in 2200 days

#4 posted 12-30-2015 03:28 PM

If you are going to varnish an outside door – I do the following with good results

Dilute tung oil by 50% with mineral spirits – apply 2 coats
Dilute tung oil by 50% with poly (oil based) – apply 2 coats
Dilute poly by 25% with tung oil – apply 2 coats
one final coat of oil based poly – this can be brushed or sprayed

Apply with rags, not brushes (except the last coat of poly) – handle the oily rags carefully – open them up and let them dry outside
Use a good tung oil. Sand between coats gently with 600 grit wet sandpaper – use dry for the first (tung oil only) and use wet with mineral spirits after the poly mixes.

If you can (warm weather) put the door in the sun to cure for an afternoon between coats.

It is a bit of work but looks great and should weather well – have used this on boats. The addition of the tung oil turns the poly into an exterior finish.

-- David in Damascus, MD

View LarsCA's profile


16 posts in 2652 days

#5 posted 12-30-2015 04:55 PM

Thanks for all of the advice. Since I have already started finishing the door with the Varathane oil-based satin finish, I think I will continue with that, as a marine finish seems to be a bit of overkill to me, since the door will never experience direct sunlight and is well protected from rain. Also, I am in a dry environment where the humidity is normally low all year – even in wet years. Also, our normal temperature extremes range from a low of 40° to a high of about 88°.

I will try to find the other finishes, especially the tung oil (which I know is available), but I do want to avoid a high gloss or semi-gloss finish and prefer the look of satin. Will I get that with tung oil? Will it be okay to put tung oil over the Varathane?

The exterior finishes that I have found so far were water-based, which is one reason I used the oil-based interior finish. I could try to order a different finish but would have to confirm whether they would ship to California. I am very close to Marina Del Rey (about 4 miles away), and so I would think that I could find some kind of marine finish there if I looked around, but we do not want a high gloss finish, and most marine finishes that I have seen were too glossy.

The weather is not warm right now and is about as cold as it can get: high of 61° and low of 42°, but it is mostly sunny. I may have to wait a few weeks for warm weather.

I am okay with touching up the door finish every year or so, if that will be necessary in order to get the satin finish I want. I think glossy finishes are more difficult to touch up.

I will share this info with my brother. Thanks again!! This has been very helpful.

View LarsCA's profile


16 posts in 2652 days

#6 posted 12-30-2015 07:03 PM

Here is a photo of my existing door, to show how it is set back from the front of the house. On the left, the house extends quite a bit forward, giving even more protection from sun.

View LarsCA's profile


16 posts in 2652 days

#7 posted 01-05-2016 06:45 PM

We finished our door and I met with the installer this morning who told me that I need to put a Spar Varathane Marine oil based finish on the exterior of the door, but he said that I can do that after the door is installed, and that it can go over the finish that we have already completed. As it turns out, the door is 1/2 inch to tall, and he will have to plane it down to fit, hopefully just on the bottom. I guess he will then put a sealer or some sort of finish on the bottom before installing the bottom piece. He also said that we do not have to put the marine finish on the inside of the door, but he did not like the way we had finished the door, as he was able to see brush lines. Those are only visible when the door is lying flat, and when it is vertical, I cannot see them. If anything like that bothers me, I can sand them out and put a bit more finish on the door, but I think I will be fine with it as it is. He also said that I should have used a stain conditioner before staining the door. I guess I am not as picky about the look as he is. He is from Encino, where the doors tend to be larger. He also said that he prefers the water-based interior finishes to the one we used, but since we did all of the finishing outdoors, I think what we used was okay – at least for the interior side. I was unaware that we could put two different finishes on one door.

View dhazelton's profile


2292 posts in 1720 days

#8 posted 01-05-2016 07:40 PM

I think you’ll be fine. Leave it alone for a year and see how it holds out. Marine varnish fails too (anyone with a wooden boat would scrape, sand and revarnish annually). Your exterior environment is not much different than an interior environment to someone like me in the northeast that I think an interior finish will hold up.

Years ago I went to pick up some sky blue paint for my porch ceiling. After I was done I noticed it said ‘interior.’ D’OH! It still looks great and our temp swings have been between 12 below and 104 above, and we’ve had three hurricanes, too.

View LarsCA's profile


16 posts in 2652 days

#9 posted 01-05-2016 09:30 PM

Thanks! That is good advice. I was planning to do a touch-up after a year anyway. The installer said that the door needed protection from humidity (we have very little of that, except today), and from UV, even though I told him direct sunlight does not every come anywhere near the door. The brightest light reflected from the house across the street, and that is minor. Since the finish I used is recommended for floors, I felt that it should be sufficient my door. Whatever the result, I think that it will be fixable in case I have done something wrong.

The installer is very young, and I think he might be trying to oversell or is being over-cautious. I do feel that he will do a good job of installing, however.

I’ve been through hurricanes when I lived in Houston, and we have nothing close to that here. When it rains here, there is generally no wind.

View dhazelton's profile


2292 posts in 1720 days

#10 posted 01-05-2016 10:04 PM

You did nothing wrong. There is so much overthinking of finishes on this site that it can make your head swim.

View LarsCA's profile


16 posts in 2652 days

#11 posted 01-11-2016 08:48 PM

We got the door installed yesterday, and here’s how it looks:

from the outside. Now that it is up and in bright light, I can easily see my brush marks, and so I guess I will need to sand the finish (exterior side only) and apply another coat. The installer said I should use Minwax water-based Spar varnish, but I do not think that will give me the look I want. I am afraid it might look cloudy, plus I do not want a gloss finish and prefer satin, which I think comes out better with an oil-based finish. I like the finish I have, but it just needs to be evened out, and I think I can accomplish that with the finish I started with. However, I will have to wait for dry weather. One advantage to the water-based finish is that it dries faster, but I do not think that is a huge plus.
Here’s the door from inside:

View dhazelton's profile


2292 posts in 1720 days

#12 posted 01-11-2016 09:08 PM

If you have several coats on there and you just want to get rid of brushmarks sand it with very fine paper or 0000 steel wool and give it a coat of paste wax.

View LarsCA's profile


16 posts in 2652 days

#13 posted 01-11-2016 11:19 PM

Thanks! I do have several coats, and it would be much easier to use the very fine sandpaper, which I already have, and I also have paste wax.

View BurlyBob's profile


3487 posts in 1689 days

#14 posted 01-11-2016 11:23 PM

Lars, that’s a great looking door. I love the color of the wood.

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