Spar Urethane Help

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Forum topic by wikdwood posted 10-21-2014 03:43 PM 1088 views 0 times favorited 9 replies Add to Favorites Watch
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2 posts in 1336 days

10-21-2014 03:43 PM

I’m somewhat new to woodworking, especially the finishing side, I have been building some outdoor furniture using some pallet wood that I’ve sent thru my planer. The 2 specific pieces that I have a problem with are 2 benches I made. The first I stained the wood using water based dyes and then covered with helsmans spar urethane. After about 6 months of being under a porch, the colors are fading. The second, was a bench that I did for my mother for mothers day. I alternated every other board with stain and non stain, putting the same urethane on the unstained boards, the urethaned boards are now starting to gray. What could I have done wrong, I followed the instructions exactly.

9 replies so far

View mahdee's profile


3888 posts in 1790 days

#1 posted 10-21-2014 05:14 PM

I have had the same issue with it. It can not tolerate the Sun at all. I switch to spar varnish.


View Fred Hargis's profile

Fred Hargis

4998 posts in 2516 days

#2 posted 10-21-2014 05:18 PM

I’ll give you my opinion of what went wrong: you used Helmsman spar varnish. Any outdoor finish that has urethane resins in it should be passed over for outdoor use. Urethanes break down quickly in a UV rich environment, causing flaking, peeling, and general deterioration of the finish. It gets a worse with dyes because they aren’t light-fast, they fade in sunlight as well. For the finish I usually recommend 2 alternatives: either a true marine spar varnish (at marine suppliers) such as Epifanes or any of several other top notch names. Or paint. The paint in this case would be the higher number base used for mixing the darkest of colors: typically #4 (05 maybe #5) but you get it without tint. What happens is most of them will actually dry clear, the oil based ones (which I prefer) look all the world like varnish with a slight amber cast. Because oil based paints are getting harder to find, some folks have try using the acrylic bases, and that seems to be working as well. Some of the bases don’t dry clear, so it’s best to use those that others have tried….or you tried yourself. I know that Olympic Icon acrylic (Lowes) #5 dries clear (almost water clear) despite the fact that it looks quite milky in the can and when applied. SW A-100 acrylic #4 also dries clear, as does their oil based #4. For color, stains have pigments which are light fast, or the color from a dye may last a little longer under the finishes I mentioned. For more info about the paint base, check this out.

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

View gfadvm's profile


14940 posts in 2713 days

#3 posted 10-22-2014 12:58 AM

I have had the same experience with Helmsman Spar Urethane. The sun destroys it in short order despite the label claims that it contains “UV Blockers”.

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

View Manitario's profile


2630 posts in 2905 days

#4 posted 10-22-2014 01:30 AM

As others have said, the problem was that you trusted Helmsman Urethane. I’ve never had a good result from it for outdoor projects; at best I’ll get a year out of it before it peels. Try one of the two part marine varnishes for better results.

-- Sometimes the creative process requires foul language. -- Charles Neil

View Rick  Dennington's profile

Rick Dennington

5908 posts in 3217 days

#5 posted 10-22-2014 04:26 AM

Use Exterior/ Marine Super Spar Varnish on all out door projects….2-3 coats should do the trick….Stay away from urethanes… good for the outdoor elements…...You’ve already found that out…!!!!!!!!!!!!!!

-- " At my age, happy hour is a crap and a nap".....

View JAAune's profile


1802 posts in 2339 days

#6 posted 10-22-2014 04:41 AM

Check out Le Tonkinois. I’ve not used it on projects yet but have done some tests involving placing objects inside cars during the summer heat and it survived. An acquaintance informed me he’s had it on an exterior door for three years and it’s still in good condition.

-- See my work at and

View wikdwood's profile


2 posts in 1336 days

#7 posted 10-22-2014 05:31 AM

Wow, and here I thought I used the right stuff, proof that you can’t always trust the label, but at least I know it wasn’t me that messed up, I really appreciate all of the information from everyone, I’ll have to try these to see which one I like best, I read that article Fred, very informative, I think I’ll try that first, thanks again everyone

View Fettler's profile


200 posts in 2019 days

#8 posted 10-22-2014 09:19 AM

I’m not familiar with that product but if its an outdoor varnish it has a UV additive. Likely you just didn’t add enough coats. Think 12 coats min. I like to use Epifanes varnish for exterior finish because no matter how many coats you eventually have to re-apply once a year. You know its good when you buy it at a marine supply store.

Just light sand and re-applying 3-4 coats a year and you’re good.

-- --Rob, Seattle, WA

View Fred Hargis's profile

Fred Hargis

4998 posts in 2516 days

#9 posted 10-22-2014 11:08 AM

Wow, and here I thought I used the right stuff, proof that you can t always trust the label

- wikdwood

That is true of almost everything in finishing products: “tung oil” that doesn’t have a drop of tung oil, waterborne finishes being called everything from “lacquer” to “polyurethane” (waterbornes are predominantly acrylic), wiping varnish being called a long list of stuff, and on and on. One other thing:any of these finishes will need maintenance over time in the outdoors, but the proper ones will make that maintenance window much longer.

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

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