clearcoating wood

Are you staining the wood first?
If so, you need to let it thoroughly dry first, which can take a few days for some.
If you're not staining, then you might have some sort of contamination issue,
I never have a problem with new clean wood, that's dry.
You should be able to spray wood just like a car.
 
Ugh, I feel your pain. I went through this last summer with oak bedwood. What kind of wood are you using? I put 3 coats of epoxy resin on the wood to seal the pores, then block sanded, shot UC and still got bubbles. Sanded and re-cleared a few more times with popping bubbles and a dropping on the clear in the crater with a tiny brush. Then block sanded and buffed.
I would read this thread and follow Jim C's advise.
http://www.spiuserforum.com/index.php?threads/clearcoating-bed-wood.5524/
 
closed grain wood like maple are easy, grainy woods like oak are always a bear. it really comes down to the type of finish you are going for. if you are just trying to put a finish on the wood and still have the grain like you typically would have on furniture then that would be no problem but if you are trying to fill the grain on something like oak and end up with a sheet of glass type finish then you will need to start with a clear epoxy to fill the grain. the bubbles come from the clear flowing down into the grain and the air in the pores bubble up.
 
Jim C said:
closed grain wood like maple are easy, grainy woods like oak are always a bear. it really comes down to the type of finish you are going for. if you are just trying to put a finish on the wood and still have the grain like you typically would have on furniture then that would be no problem but if you are trying to fill the grain on something like oak and end up with a sheet of glass type finish then you will need to start with a clear epoxy to fill the grain. the bubbles come from the clear flowing down into the grain and the air in the pores bubble up.
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something i was wondering when reading through here:
i havent done much auto clear on wood and not on open grained/pour woods but quite a bit of poly and varnish. they seem to be a bit thinner than cleacoats. the woods with wider grain/open pours(oaks and ash mostly that ive used but im sure there are more) the poly/varnish seems to sink into the grain/open pours instead of trying to bridge it.
would it be possible to reduce a clearcoat to help it sink into the pours/grain?
 
tomsteve said:
something i was wondering when reading through here:
i havent done much auto clear on wood and not on open grained/pour woods but quite a bit of poly and varnish. they seem to be a bit thinner than cleacoats. the woods with wider grain/open pours(oaks and ash mostly that ive used but im sure there are more) the poly/varnish seems to sink into the grain/open pours instead of trying to bridge it.
would it be possible to reduce a clearcoat to help it sink into the pours/grain?
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sure you can reduce the clear and you will have to put less on for it to flow into the grain BUT remember that the solvents flash off and then it will leave the grain open again so you might have to put twice as many coats on to fill and seal the grain so air bubbles dont rise. best thing to do is take epoxy like what shine is using, pour a little on the surface then take a bondo spreader and squeegee it into the grain. remove all of it from the wood surface. basically scrape it clean. let that epoxy stiffen up for a couple few hrs but not completely cure. repeat that one or two more times to completely seal the grain. once the last coat you squeegee on has stiffened up then pour the final coat on. burst and airbubbles with a torch or heat gun. let that cure for a day or two. if it looks good then you can leave it. if you want to at that point you can sand it down flat then clear with universal clear. basically what your doing here is using a 100% solids epoxy to work as a clear grain filler before you do your final finish. btw, the grain filler doesnt have to be epoxy. if it doesnt need to be clear you can make it easy on yourself and use a trowelable grain filler. they have this at home depot. its parks wood filler for floors. spread it on to fill the grain, let dry, sand smooth and stain and finish the wood as you normally would.
 
I use conversion varnish on all my cabinet projects, it's so easy to use and it's a 2k product
just for wood. I also use a "vinyl sealer" first, a couple coats of sealer, wait 30 min. sand the
sealer and then a couple coats of CV and you're done. Only way to go
for cabinets and furniture.
 
So Dude, what sort of wood & on what intended use applications? more details can get a better answer for you personally.
Occasionally prefinishing different sorts of woods on exterior & interior home doors at work has had different experiences. As Jim says, closed grain woods are easy. Some mahogany is much easier than others. Then some oaks are much worse than others.
If trying to get oak glass smooth with no grain showing, that will take one of the methods Jim mentioned & extra patience. Bursting bubbles with heat gun , torch , or even hair drier can be a huge help.
If wanting to leave grain, I've did more thin coats & been good with automotive clear. Bubbles popping through thin coats don't show up as much with heavy woodgrain left showing.
I've had envirotex used on a part time use car dash turn to sticky muck from only a little florida sun in my personal experience. I'd coat any exterior epoxy with something uv resistant afterwards.
At work I have recently tried masterclear supreme, which is a waterbourne clear because of problems with automotive clear flattners hazing in wood. It seems pretty good for some applications , easy to use, uv lights kick it off fast, & seems reasonably durable for what I'm doing. But is it as tough as the spi clear? Efff no.:(
 
Jim C said:
sure you can reduce the clear and you will have to put less on for it to flow into the grain BUT remember that the solvents flash off and then it will leave the grain open again so you might have to put twice as many coats on to fill and seal the grain so air bubbles dont rise. best thing to do is take epoxy like what shine is using, pour a little on the surface then take a bondo spreader and squeegee it into the grain. remove all of it from the wood surface. basically scrape it clean. let that epoxy stiffen up for a couple few hrs but not completely cure. repeat that one or two more times to completely seal the grain. once the last coat you squeegee on has stiffened up then pour the final coat on. burst and airbubbles with a torch or heat gun. let that cure for a day or two. if it looks good then you can leave it. if you want to at that point you can sand it down flat then clear with universal clear. basically what your doing here is using a 100% solids epoxy to work as a clear grain filler before you do your final finish. btw, the grain filler doesnt have to be epoxy. if it doesnt need to be clear you can make it easy on yourself and use a trowelable grain filler. they have this at home depot. its parks wood filler for floors. spread it on to fill the grain, let dry, sand smooth and stain and finish the wood as you normally would.
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thanks,jim. great advise and a few things i hadnt thought of. with oak, i dont use a filler unless its a table top. i noticed some time ago on oak tables the finish would be delaminating/failing/looking rough. looking closely i realized it was because the grain wasnt filled so when the tables are cleaned or spills happen, some of the spill and cleaning stuff goes into the grain where there may not be finish and causing problems.those tables had very thin finishes on them-not sure what but very thin. i started filling grain with wood filler before finish but never did care for the look of those fillers. never though of using epoxy for the occasion but it sure makes sense- it seems it would leave a bit of the depth that open por woods have.
now i gotta find someone that wants a table.;)
 
yes you are right! on exterior wood that sees weather..like a door, you really want to fill the grain because every open pore is a place for water to eventually get behind the finish and cause failure. i have used that parks filler quite a bit on oak and was worried you would see the filler in the pores but if your staining after its applied, you cant even tell there has been filler applied. the filler soaks up the stain really well and becomes the wood color. it totally disappears. im sure other fillers may vary with this but i have had good luck with that stuff.
 
Lots of great advise! Thank you all. I helped a guy stain oak wood with an oil based stain, IIRC. Let dry overnight. Then he found some water thin epoxy for wood, I don't remember the brand. We brushed on 2 coats. Let dry overnight,. Then I applied 2 coats of DC 2000 on the bottoms. I don't remember that having any issues. For the top side I applied 8152 clear in thin coats trying to avoid this but it started to bubble very quickly. The reason for PPG is the shop was a sponsored resto shop.

I ask because I'm on my own now and wanting to do musical instruments and other wood. Does anyone know about Cardinal brand polyester grain filler / products? The shop had got some of that but didn't use it.
 
i have never used it. i dont think there is a ton of difference brand to brand when it comes to pore or grain fillers. there is one that i have wanted to try for awhile called aquacoat. its waterbased and its clear. says its like a gel. next time i have a job where i need to do this i am going to try that stuff out.
 
Dude, you just told me one problem with your procedure, letting oil base dry only overnite, though in that example you said it was ok. .Oil base stain needs a lot more dry time not to risk issues as it is not so forgiving with higher end topcoats..
At work I use a bit of Lenmar lacquer base stain, which does dry quick and has been compatible for me mixing with spi clear to do a little shading in the first layer or 2 of topcoat. In some cases I've went to clear in less than an hour, NOT with a wood like oak though. Have even gotten away with this stain not truly dry on samples under automotive clear since solvents are similar enough.
With something like guitars, you'll generally use woods like tight grained mahogany , birch, maple for body, & ebony or rosewood mainly for fingerboards. Even a tighter grained mahogany will need grain filler for a glass smooth application, but many of your other common choices won't. Can just sand clear a little between coats OR as someone here with a little more airbrush skill than me:p said, Intercoat clear makes a badass sanding sealer. Look up some of JimC's older posts such as in the show & tell section or his instagram pics. Should inspire ya.
 
I always prefer to stain the wood first, before I want to paint it. Especially if it's an oak. And if we would consider about the best oil for wood working or wood finishing job, I can highly recommend this resource ( here: https://www.wood-turned.com/best-oil-for-wood/ ), which I've found two weeks ago. It has dozens of different options to choose from, with all the specifications needed.
 
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Never shot clear on wood, but various grades of poly. I agree the grain will soak it up and bubble. To get around this i started laying a wet coat and walk away. Let it dry well to seal up the grain. Tack it off and start laying additional coats.
Anytime i try to build coats, without letting the first coat cure, it would continue to soak in, continue to bubble, not build well.
Reduce it just enough to shoot well.
 
If you wanna fool around, use slowest reducer you can, throw some copper or gold pearl in the poly. The wood draws the poly into the grain, the pearl will flow towards that / concentrates in those areas and creates great patterns. Its unpredictable, test it first to get a feel. Works best on open grain.
 
Indyjps said:
If you wanna fool around, use slowest reducer you can, throw some copper or gold pearl in the poly. The wood draws the poly into the grain, the pearl will flow towards that / concentrates in those areas and creates great patterns. Its unpredictable, test it first to get a feel. Works best on open grain.
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yes first coat needs to soak in and dry to plug up all the grain. the spi intercoat clear works great for this. basically using it as a sanding sealer. its dry and sandable in 10 min or less. a coat or two, light sand and you have a smooth surface, ready to go.
 
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