How do I restore and maintain my wood front door?
December 14, 2014 2:06 PM   Subscribe

Our house has a really nice front door, which appears to be made out of wood. It looked amazing when we moved in a few years ago. The outside part which is in the sun all the time now looks dull and faded. Pictures within.

It's a little bit hard to full capture in pictures, but I tried here: inside (good) and outside (bad). The outside part used to look like the inside, so it's not just a different finish. And, indeed, the parts of the outside that are covered when the door is closed look the same as the inside. You can kind of see that effect here, but it was hard to get the lighting right to make it show up without exaggerating it.

What can I do to restore the outside to its former glory, and to prevent this from happening again? I'm guessing the door is only 3-4 years old, so it definitely should not be due for replacement. I'm a little surprised it looks this bad so soon (but we didn't install it, so I don't have any details about where it came from or how it was made). Does it need to be re-stained or something? Is it normal for this to need to be re-done so soon? We live in a dry climate, so it's not exposed to much rain or anything; just sun and heat.
posted by primethyme to Home & Garden (12 answers total) 1 user marked this as a favorite
What? No; you don't replace it, you care for it. It needs to be stained and varnished or oil waxed, probably annually.
posted by DarlingBri at 2:37 PM on December 14, 2014 [1 favorite]

I'm guessing that what happened is that it was finished with a crappy varnish that either was not or should not have been rated for exterior use. Ultraviolet light from the sun is an absolute killer for varnish and similar coatings, and UV-resistance is one of the main differences between interior and exterior grades.

Adding UV protection also pushes up the cost of manufacture, which is why interior varnish lacks it, and is cheaper. That cheapness is why people are sometimes tempted to use it outdoors, especially if they know they won't have to live with the consequences.

I'm guessing that the solution is going to be to strip and refinish the door, using a better grade of varnish, and that everything will be fine after that. With an appropriate varnish, the finish should look good for a long time.
posted by Anticipation Of A New Lover's Arrival, The at 2:40 PM on December 14, 2014

Clear finishes do not hold up well under UV, so it's the sunlight that is doing in your door. If you knew what was on it already, you could just put on another coat. From what I can see from your interior shot, it doesn't look like a high-gloss polyurethane, I would guess some sort of a penetrating oil + varnish finish, such as Watco oil. If that's the case, all you need to do is to wipe on a coat or two - you don't need to sand before hand. You should use an unpigmented product as you just want to add gloss but not change the color.
posted by mr vino at 2:40 PM on December 14, 2014

Our nice solid wood front door faces west and gets the full brunt of afternoon heat & light (probably similar to yours). I've had to refinish it every 2 years to keep the marine varnish looking fresh. Finally decided to strip it and paint it, and I haven't needed to care for it in 5 years. Still looks good, no regrets.
posted by artdrectr at 3:08 PM on December 14, 2014 [3 favorites]

We just did this for our door, which also faces west, so is in the worst position for a wood door. If your varnish is degraded enough that you can run your finger down the wood and get some color transfer to your finger, I would go through the sanding and staining process before applying a spar urethane to the outside. If you are using a good outer sealing coat, like a spar, you should not have to re-sand and re-stain very often, but you will have to reseal every year or so. (This time we waited 4 years, and we had to go through the whole process again). My personal opinion is that a gloss urethane offers more protection than a satin or semi-gloss, but I have no real data to back up that claim.
posted by blurker at 3:15 PM on December 14, 2014 [1 favorite]

You need to apply teak oil annually. Teak Oil is just one of many brands of wood maintenance products, at the end of the day, you could use olive oil. Experts claim linseed oil is the best. But whatever you use, you need a lot.
Varnish is another solution which looks good, but is not as stable as a deep oil treatment.
For detailed advice, go to a ship-builder. They love their good maintenance.
posted by mumimor at 3:45 PM on December 14, 2014 [2 favorites]

If your going to polyurethane it the generic term for the product you would use is Spar Varnish. However not all spar varnishes are spar varnishes, for instance Minwax Helmsman Spar Urethane is crap compared to something like Pettit Z-Spar Captain's Varnish. Unfortunately real boat varnishes are high gloss only.
posted by Pembquist at 5:13 PM on December 14, 2014

Are you sure it's real wood? It almost looks like my Therma Tru door.
posted by Ostara at 5:18 PM on December 14, 2014 [1 favorite]

Like Ostara, I'm doubful it's actually wood. The pics don't show enough of the door for me to feel confident either way, but the surface texture doesn't change in places where I'd expect it to change if it were cut from solid wood.
posted by jon1270 at 5:37 PM on December 14, 2014

I'm with Ostara and jon1270 re the door composition. It doesn't have to be real wood to look good, but will require different finish, of course.
posted by she's not there at 7:56 PM on December 14, 2014

The main advantage of oils over urethane finishes is that oils can just be reapplied as necessary with no prior surface prep beyond simple cleaning, but urethane looks crappy and doesn't stick properly without sanding down first. Degraded oil finishes also tend to thin, dull and fade while degraded urethane will go milky and eventually blister and flake.

Linseed oil is traditional and competent, but will darken wood. If you don't mind that, it's cheap, easy and good. It also has a really messy polymerization chemistry that handles UV reasonably well - for a year or so, UV will create as many new cross-link bonds as it destroys in a linseed coating.

Tung oil is more expensive than linseed, lasts rather longer before needing reapplication, and darkens less.

The main advantage of a urethane finish is that it will last maybe three or four times as long as oil before needing a redo. On the other hand, it only takes ten minutes to oil a door.

If you're going to use a drying oil like linseed or tung, just wipe it on with a rag, give it a couple of hours to soak in, then rub it over with another rag. Do that twice, a couple of days apart. Spread the rags out and hang them up outside - don't just wad them up and chuck them in the bin or they might spontaneously combust.
posted by flabdablet at 6:23 AM on December 15, 2014 [3 favorites]

This is just to say that flabdablet's spontaneous combustion warning was totally not a joke. Drying oils like linseed and tung will auto-polymerize, meaning that all by themselves they'll go from a thin, oily liquid made of lots of short-chain molecules to a hard, shiny solid made up of long-chain molecules.

This is great in terms of wood finishing and is why they're so popular in that craft, but there's a catch: the auto-polymerization process is exothermic. It creates more heat than it uses. Some of that heat will dissipate into the air, and some will be transferred to whatever the oil is on (e.g. the rag you just used) and heat it up a bit. As you likely know, more heat makes most chemical reactions (like polymerization) go faster, so if more heat is going into the substrate than is escaping into the air (such as when the rag is left balled up in a hot shed) you can run into a positive feedback loop where the reaction runs faster and faster and hotter and hotter.

Both linseed and tung oil have very low flash points (222°C and 289°C respectively) and it's far from unknown for a carelessly-discarded rag soaked in one or the other to get hot enough to touch off the oil all by itself (usually a few hours after you've walked away and forgotten about it) and then you have a big problem that is likely to get much bigger very soon! I used to work with a lot of linseed oil, and I've seen the rags start to smoke when left out in the sun on a hot day.

Best practice for oily rags like this is to soak them in water and then spread them out, outside on some concrete, well away from anything flammable. They'll be dry by the next day and then you can deal with them safely. That's good enough for a door at your house, anyway; commercial operations that use a lot of linseed or tung (or epoxy, but that's a different story) have more stringent requirements, but the above is fine for occasional home use.

Also, look up application methods if you decide to go with oil. Sometimes it is recommended to dilute the oil in a solvent of some kind to aid application. Just worth a quick Google search to see.
posted by Anticipation Of A New Lover's Arrival, The at 7:43 AM on December 15, 2014 [1 favorite]

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