Durable outdoor finish

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Forum topic by Dabcan posted 03-26-2014 12:07 AM 2180 views 1 time favorited 12 replies Add to Favorites Watch
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255 posts in 4130 days

03-26-2014 12:07 AM

Topic tags/keywords: outdoor finish blo spar varnish poly bird house water oil

I’ve been making birdhouses for the last 2 years, and I’ve tried various brands of spar varnish as well as one type of water based finish. All are meant for outdoor use, and all have worked well. My problem is the water based finish dries fast, and looks fine on lighter woods, but really doesn’t do much for walnut (which I am using more and more). So I’ve been using the spar on the varnish, but it takes about 10 hours to dry, and the last can I bought smells like a urinal (it also wasn’t satin as the can said, and yes I stirred it… a lot). I also find the spar looks horrible almost like a plastic film over top of the wood.

Am I asking too much for a durable outdoor finish that doesn’t look bad? i’ve done a few rifle stocks in BLO and they look great, but they don’t sit outside year round. BLO would be the look I’m hoping to achieve, but more durable.


-- @craftcollectif ,,

12 replies so far

View TechTeacher04's profile


495 posts in 2990 days

#1 posted 03-26-2014 12:56 AM

That is the issue with finishes that survive UV rays, spar varnished simply do not last, they must go on think to create a barrier for water and to block the suns harmful rays. Another option is changing the species of wood you build he birdhouses out of. I cringe thinking of using walnut outside. It is one of my favorite woods to work with. Teak, cedar, some oaks and locust all hold up well in the sun and weather, however even these species will need periodic refinishing. Another school of thought would be to leave the wood raw, provided you use a species like I listed that will hold up better in the elements and let the wood gray like nature intended.

View gfadvm's profile


14940 posts in 4149 days

#2 posted 03-26-2014 01:41 AM

I built some wren houses from Hedge (Osage Orange for the Yankees here). It has held up amazingly well with no finish at all. It doesn’t even look weathered after 5 years.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Dabcan's profile


255 posts in 4130 days

#3 posted 03-26-2014 01:57 AM

I’ve done a few with birch and a thin water based finish, but I have one model that needs a nice dark wood to contrast. I wonder if I should retry the spar but thin it down more

-- @craftcollectif ,,

View mesquite22's profile


42 posts in 4128 days

#4 posted 03-26-2014 02:35 AM

This works well

View Fred Hargis's profile

Fred Hargis

7481 posts in 3952 days

#5 posted 03-26-2014 11:20 AM

A couple of thoughts. Your comment about the “plastic look” sounds like it’s a polyurethane formula varnish. Urethane and UV do not get along well, if you check the high quality marine grade spar varnishes you’ll see they are all may with other reins, usually an alkyd resin. “Spar” doesn’t mean the finish has UV protection, it refers to the amount of oil in the basic formula. Spar is “long oil” meaning it has a higher oil content when made, which gives makes the finish softer and more flexible. The marine grade spars do have UV protection for that application. Waterborne finishes may be labeled as “urethane” but they are all (one exception) really an acrylic finish, and one labeled with UV inhibitors should be acceptable for your use if it’s otherwise suitable. (The one exception may be water borne shellac, which apparently uses shellac resins.) So, if the acrylic finishes don’t give you the look you want, you may well be stuck with an oil base. If that’s the case try a marine spar like Epifanes. There is one more option you can try: exterior oil based paint base (without tint). Buy a quart of the paint base and try it, it looks very much like varnish once dry (clear), is less expensive, and holds up well outdoors. I used it on cedar bird feeders for many years. If you choose this, it’s best to test the base first by putting some on a paint paddle and letting it dry, not all of them dry clear. One I know for sure works is the Olympic exterior oil base #5, but Lowes has stopped carrying it. I intend to try the Benjamin Moore version (theirs would be #4)...but you want the base that used for the darkest paints, in most brand that would be #4. Be aware, any clear outdoor finish will need repair over time, but the marine spar and/or exterior oil give you probably the most life of any. (my opinion, of course).

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

View dhazelton's profile


2839 posts in 3755 days

#6 posted 03-26-2014 12:16 PM

If you are making birdhouses for birds to actually use I wouldn’t worry about finish. I made a few out of scrap pine years ago, sprayed them with some old red primer so they would look barn red and put left over shingle material on the roofs. They have held up really well and have raised lots of peeping babies.

View Gerald Thompson's profile

Gerald Thompson

1312 posts in 3693 days

#7 posted 03-26-2014 04:06 PM

Ipe. It will not rot, burn or float. It is very, very heavy and will dull tools quickly.

-- Jerry

View b2rtch's profile


4922 posts in 4507 days

#8 posted 03-26-2014 04:23 PM

I have the same question for an outdoor table made of ash wood and pine.
I do not want to let turn grey, what can I use?
Same thing that Fred recommend?

-- Bert

View Fred Hargis's profile

Fred Hargis

7481 posts in 3952 days

#9 posted 03-26-2014 05:04 PM

Bert the UV inhibitors in the marine spar and the untinted paint base will do just that, keep the wood from turning gray. But be aware of the need to re do any of these finishes over time…those I mentioned should give the maximum life before you have to do it.

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

View b2rtch's profile


4922 posts in 4507 days

#10 posted 03-27-2014 01:44 PM

Thank you Fred

-- Bert

View redSLED's profile


790 posts in 3351 days

#11 posted 03-27-2014 11:04 PM

Maybe design your bird houses with oversized roofs (the overhang will give added sun and weather protection to the main structure) that you attach unfinished cedar shingles to – and replace the cedar shingles every 3-5? years or so when they degrade enough. Then that guy named Bob somehow becomes your uncle.

-- Perfection is the difference between too much and not enough.

View joeyinsouthaustin's profile


1294 posts in 3531 days

#12 posted 03-28-2014 09:40 PM

This may be well out of reach, but I have started using a post catalyzed product with uv protection for my exterior doors. It is by MLcambell. They call it EuroX. It gave the oak doors I just finished a nice deep satin sheen, that actually looked quite similar to the waterlox the rest of the interior oak paneling was finished with on the job. It is technically a 2 part poly based formula. It has been formulated over years in the Mediterranean, and is tuff, and uv resistant. Downsides… it is very expensive, very toxic (until cured) and requires equipment and experience to mix and spray post catalyzed products. But if you want Birdhouses that will stand up like a teak door on the beach in full sun, it is the stuff.

-- Who is John Galt?

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