Author Topic: Problem with spar urethane finish  (Read 1033 times)

Offline kiltedcelt

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Problem with spar urethane finish
« on: January 04, 2010, 12:03:00 PM »
I'm finishing up a couple bamboo backed ipe bows and I applied a first coat of Minwax spar urethane last night around 4:30 PM. This morning at 7:30 it was still tacky to the touch in some areas. My temps in my apartment are not below about 72 - 75F and not humid by any means. This is the first time I've ever used spar urethane. I wanted to get a nice glossy finish but now I'm wondering what I've gotten myself into. How should I go about correcting this problem? I'm thinking if it hasn't dried 10 hours after applying it, it probably isn't GOING to dry. Could I pop the two bows into my heat box and set the temp as low as possible - say 90 degrees for an hour or so and see if that does anything, or go over them with my heat gun on its lowest setting (or a hair dryer)? The finish is tacky in some areas but seems alright on others. However, more of the finish is tacky than isn't. Can a rag soaked in mineral spirits take this stuff off? A guy at the wood working store suggested a chemical stripper but I'm really wary of that and what it'll do to the Smooth-On. I guess I could try sanding it all off but that just seems like the worst possible way to go. If the finish isn't dry by the time I get home from work this evening I'll know for sure that something is wrong. At that point it'll have been on for a full 24 hours or more. These ended up being a couple of really beautiful bows - I don't want to screw them up when they're practically finished. Advice, suggestions? Oh yeah, the urethane sat in a freezing cold car for 4 hours but warmed up to room temperature for 24 hours before I openned the can. Oh yeah, and openning the can - whoo! Something was wrong there because the lid was on so tight I pretty much ruined it getting it off. I finally had to use a pair of pliers to get the lid off and after that it wouldn't go back on tight so I had to place a plastic bag between the lid and the can to make sure it'd stay sealed properly. However, now I'm wondering if the urethane is somehow bad. Maybe I'm better off just stripping the stuff off and putting on Tru-oil or Teak oil or something similar. I ultimately want to get a glossy finish.

Offline K. Mogensen

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Re: Problem with spar urethane finish
« Reply #1 on: January 04, 2010, 01:08:00 PM »
I would like to know this too. I just finished staining a bow rack a real nice Dark Walnut color and sprayed it with three coats of this stuff. It is still very slightly tacky, and it attracts dust and dog hair like a magnet. Very frustrating.

Offline Robertfishes

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Re: Problem with spar urethane finish
« Reply #2 on: January 04, 2010, 01:15:00 PM »
I would give it more time to dry before doing anything to it..I use the Minwax brand in the shaker spray can and have a dehumidifier in my spray finish room. I had a bow take a full 2 days to completly dry once,dont know why..just weird science I guess??? never worked with ipe, is it oily?

Offline George Tsoukalas

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Re: Problem with spar urethane finish
« Reply #3 on: January 04, 2010, 01:34:00 PM »
Give it time. Put it near a heat source. Jawge

Offline Art B

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Re: Problem with spar urethane finish
« Reply #4 on: January 04, 2010, 02:17:00 PM »
Did you clean your bow first using a thinner? If so what kind? Also, did you use a tack rag to clean off any dust? I've had drying problems cleaning with the wrong thinner and using cheap tack rags from Wally World.-ART

Offline Jason Scott

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Re: Problem with spar urethane finish
« Reply #5 on: January 04, 2010, 02:45:00 PM »
Ipe, bacote etc. are oily and take a while with spar urathane.

Offline ChristopherO

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Re: Problem with spar urethane finish
« Reply #6 on: January 04, 2010, 02:47:00 PM »
Just be patient, it will dry but you've got to give it time for this application.

Online Roy from Pa

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Re: Problem with spar urethane finish
« Reply #7 on: January 04, 2010, 03:29:00 PM »
I have had the same problem with spar. I normaly don't even touch the bow for at least 3 days. And the thicker the coat, the longer it takes. A warm area will help you out.

Offline BWD

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Re: Problem with spar urethane finish
« Reply #8 on: January 04, 2010, 04:03:00 PM »
Have used it on four bows and never had a problem with it drying. Haven't tried it on a bow built with woods that need to be sealed before appling the finish coats.
"If I had tried a little harder and practiced a little more, by now I could have been average"...Me

Offline Dano

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Re: Problem with spar urethane finish
« Reply #9 on: January 04, 2010, 04:12:00 PM »
Most likely the oil in the Ipe, as said, just be patient it'll dry eventually.
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Online Roy from Pa

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Re: Problem with spar urethane finish
« Reply #10 on: January 04, 2010, 04:13:00 PM »
Ah BWD, maybe there in lies the problem. Not sealing the wood? What would one use to seal wood, before applying spar? I always make bows from Osage and Bamboo. Both very hard materials.

Offline scottm

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Re: Problem with spar urethane finish
« Reply #11 on: January 04, 2010, 04:29:00 PM »
I used Minwax spar urithane on my first self bow last summer.I took it at least a week to dry.My shop has a dehumidifier running at all time so its fairly dry.I was to the same point you are.I thought I was going to have to try to clean it off with something and start over.Just give it time it will dry.

Offline BWD

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Re: Problem with spar urethane finish
« Reply #12 on: January 04, 2010, 04:51:00 PM »
Do a search for oily wood on bowyer bench. Sound advise posted there.
"If I had tried a little harder and practiced a little more, by now I could have been average"...Me

Offline Robertfishes

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Re: Problem with spar urethane finish
« Reply #13 on: January 04, 2010, 05:08:00 PM »
The bow I had take 2 days to "dry" had .030 cocobolo veneers in the limbs. I used superglue on the limb edges (2 coats)and lightly sanded..still took a couple of days to dry on the limb edges, the dymondwood riser and glass limbs were good and dry to the touch in less than 8 hours. The directions on the can says to let cure for 24 hours before normal use...that is always hard to do...

Offline K. Mogensen

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Re: Problem with spar urethane finish
« Reply #14 on: January 04, 2010, 09:30:00 PM »
Checked my rack tonite, DRY!!!!!

Offline kiltedcelt

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Re: Problem with spar urethane finish
« Reply #15 on: January 05, 2010, 12:02:00 AM »
Thanks for all the replies guys. I talked to the seasoned older guy that runs the park district wood shop I occasionally go to and he suggested the same thing as Jawge - let it sit and dry. He had no doubt that it would finally dry but that as cold as it is right now it might take several days to dry. I live in an apartment with steam heat that alternately comes on and makes things occasionally uncomfortably warm followed by turning off until it gets uncomfortably cool. So, I've got temperature swings working against me as well. My buddy the shop supervisor said he thought as long as I had thoroughly sanded the ipe before applying the finish I shouldn't have any problems. Also I brushed it on as per the instructions and it was probably a bit thick. For future reference, he suggested applying it with a rag so that it would go on in a very thin coat that would dry much more quickly and could be easily worked in a much shorter time frame. I'll let it sit for a couple more days and see if it's getting any better over time. It's already dried on the bamboo back, but I think I had to apply more finish to the ipe because it seemed to be a good bit more absorbent than the bamboo, so I'm sure I applied it far thicker on the belly than anywhere else.

Offline bigcountry

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Re: Problem with spar urethane finish
« Reply #16 on: January 05, 2010, 02:32:00 PM »
I took some's advise and used bullseye shellac (no wax) first.  It dries very quick.  Then over that, I put my 6-7 coats of spar.

Offline George Tsoukalas

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Re: Problem with spar urethane finish
« Reply #17 on: January 05, 2010, 06:33:00 PM »
I agree about thin coats being the way to go. Let us know how it goes. Jawge

Offline Russell S.

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Re: Problem with spar urethane finish
« Reply #18 on: January 05, 2010, 11:58:00 PM »
i had the same problem with my first ipe bow.  i striped it with acetone then re sanded the bow.  next i cleaned it with acetone again, then with denatured alcohol then let it dry well.  then bulls eye shelic.  the shelac drys quick,  so i put 3 coats one.  after a day a LGHTLY sanded with steel wool i think.  then put the spar on.  it takes spar a while to dry, but after 24 hrs it was dry.  

short story, it may never cure on IPE coat with shelac first.  you dont have to sand shelac because it doesnt have any wax in it.
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