I have a lot of unfinished red oak in a bedroom I’m remodeling–doors, jambs and casings, window trim, base molding, and some 18″ X 36″ sliding doors (veneered 1/2″ ply). Since this is my first raw wood finishing project in 10 years or so, I got my feet wet by staining and polying the sliding doors. But the poly hasn’t turned out real smooth. The satin Deft polyurethane I bought for this always ran and ended up lumpy when I let the doors dry in a verticle position. Switching to horizontal drying position helped, but I can’t very well re-orient the verticle door jambs and casings like I could the doors. How can I get a smoother finish on the verticle surfaces? Should I switch to a different brand of poly? Different brushes (currently using a 3″ Linzer brush)?
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Use less on your brush, don't start in corners, go back once and brush the whole surface again to remove lap marks and runs. Work briskly, and you'll get better results by finishing the doors horizontaly. If you don't have a good brush that doesn't shed, I get great results with the better quality foam brush. It's important to go back over your work and brush it out before too long.
Scuff and the first coat with 220, after that,320 between coats. Your'e only sanding the finish.
Dave's right. Too much on the brush. Your problem is a technique issue.
But may I suggest the use of scraper rather than sandpaper. You'll end up with a smoother finish and takes less time. I use the fake plastic pads instead of sandpaper on the curves.
You'll need at least 3 coats - thin coats.
A wipe on poly would make it easier to avoid the drips as well because the coats are much thinner. The downside is that you would need more coats BECAUSE the coats are thinner. Then again, trim molding is a not being walked on so 2 thin coats might be sufficient.
Part of the problem is that you need to first sand the raw wood, then meticulously clean off the dust (vacuum, wipe with paint thinner, then a tack cloth).
You also need to sand after every coat of poly -- using the same clean up techniques to remove the sanding dust.
The other part of the problem is technique, and perhaps the brush you are using.
The best brush for poly (in this situation) would be a "china bristle" brush, or better yet, a "white china bristle" brush. In my area most of the paint stores carry a brand of the latter called Yachtsman -- which is an inexpensive, but still decent brush for casings, etc.
As far as technique is concerned, you can avoid runs and sags by "tipping off" -- long strokes with the brush at a 45 degree angle, after the entire surface (say a casing) has been coated. Until you regain the knack of applying just enough finish to the surface (so it won't sag after sitting for a few minutes), you should go back and tip off just before the poly sets up (usually about 5 minutes, but will vary with brands).
OK, I'll try all the techniques you all have mentioned.
Just to provide a little more background, I did sand everything down with 150 grit, then 220, with a random orbit sander whereever possible. Between coats I've been lightly sanding with 400 grit, wiping with a rag soaked in mineral spirits, then blowing with compressed air.
I'm sticking with oil-based stain and poly, because in my (limited) experience oil-based products generally work better.
What do you all think about thinning the poly? This Deft stuff seems very thick; I've stirred and stirred and it still has the consistency of maple syrup.
Thanks for all the feedback.
You can thin the Deft Poly with Mineral Spirits. To make your poly "wipe on" use a 1:1 ratio of Poly:Mineral Spirits. If you just want it thinner I would use 2 parts poly and 1 part Mineral Spirits.
Cheers!Dark Magneto
I would use naptha to thin it. It is a little "hot" than mineral spirits/paint thiner.
It will evaporate quicker.
I always thin oil-base poly- it just flows on more easily. Experiment a bit to determine how much to thin it. Just remember, you can always add more thinner.
On large surfaces, such as flush doors, I like to use a fine nap roller to apply the poly, and then just tip it off with a brush. It goes much faster than just trying to brush it on.
Of course, my really preferred way to do finishing is to find someone else to do it.:)
call manufacturer and see what they tell u to cut it with not all polys are mineral spirit based, tho most are if u cut w the wrong chemical it might not dry for long time, 2-3 days, or worse as you cut poly it also becomes a weaker wearcoat (less solids)
or switch to better poly for your application i use wipe-on test with a cloth to find smooth applying chemical something like fabulon is thinner viscosity, very smooth applying right out of the can, gym hardness
water borne is tough for trim if a catalyst type, batch goes hot too quick or one that requires sealer, extra coat needed usually not as strong as oilbase, less solids
I have never used the Deft poly. Most are okay straight from the can, but some are really too thick, especially for vertical surfaces. the Deft can will tell you what to use as a thinner, but I would start off with very little, and add more as seems appropriate.
I would avoid naptha; yes, it will cause the material to dry faster, but this is usually not an advantage, since the material may set up too fast to allow time for the "tipping off" step I mentioned earlier.
Personally, my favorite products for casework and doors are:
ZAR -- used to be called Quick Dry Polyurethane, but they just recently changed the name to something else (quick dry sealer or some such). This dries fast enough to apply two coats in one day, and can be used as is without thinning.
BEN MOORE: BENWOOD POLYURETHANE (Low Lustre). After two coats of the Zar, I use this for the third (and final) coat. this is one of those polys that is thicker than most; I generally use it straight from the can, but if you have problems with sags and drips, you might want to thin it slightly.
Everybody has their favorite poly products, but this happens to be the best combination I have found (after years of trying everything under the sun).
I've done a lot of field finishing on doors and cabinets, and have settled on a method that gives me almost spray-booth quality finishes. I use Minwax fast-drying polyurethane (oil-based) straight from the can.
I apply the poly with a dense foam roller - not too heavy - and go back over it with a dry (meaning not loaded with poly) foam brush to knock the little bubbles down. Two coats over unfinished wood, then a light sanding with 220, then a finish coat. On vertical surfaces I never get runs as long as the last coat is thin. On horizontal surfaces it really does look as good as a spray booth finish - especially if the sanding is done wet with 320 grit. About 6 hours to recoat, 12 hours before sanding the finish.
Remember to stir (not shake) the poly thoroughly each time you use it. The flattening agents that make it semigloss or satin tend to settle to the bottom of the can.
Beinhg that its not flooring youre polying I'd use a water bourne poly.
You could do all three coats in one day as well.
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