Bill I know you already know this but be sure and use a high quality brush and take light long strokes for the final strokes. Also don't forget to clean your brush. It will last for years.
I recently saw a video of a finishing class in which the teacher used a folded paper towel instead of a brush to apply the poly. No brush marks at all in any of the items (mostly picture frames) I've made using the method. The poly is pretty volatile, and it may have thickened from sitting open. Where you live is pretty hot so drying time has got to be pretty short, so thinning the poly a bit probably wouldn't hurt. But do try folding paper towels into a brush shape and applying each coat of poly fairly quickly.
I have been using a foam brush on the last coat. I think the drying time might be the culprit here. That plus the poly getting thicker from being open. I might try cutting it a bit and see how that works.I think it's because the finish is drying too fast. I don't remember this being a problem many years ago when finishes took 24 hours to dry but it did become a problem when they went to 1 to 4 hours drying time. The finish dries before surface tension can self level the finish. Try using it under the slowest possible drying environment and maybe use a foam brush for the final coat. Make sure you have removed the brush strikes from previous layers or they will telegraph through. Another possibility is to use a hair dryer on any brush strokes you see. It might work. It's one way to get rid of bubbles in a finish so it might smooth out brush strokes too. Otis uses a propane torch for that. It might work too but you would have to be more careful and I wouldn't use it on an oil based finish.
Tom I think you are right in saying the poly has thickened up. I am going to try cutting it a bit and see if that works. I use foam brushes but I am going to try the paper towel and see how that does.I recently saw a video of a finishing class in which the teacher used a folded paper towel instead of a brush to apply the poly. No brush marks at all in any of the items (mostly picture frames) I've made using the method. The poly is pretty volatile, and it may have thickened from sitting open. Where you live is pretty hot so drying time has got to be pretty short, so thinning the poly a bit probably wouldn't hurt. But do try folding paper towels into a brush shape and applying each coat of poly fairly quickly.
Thanks Malcolm. I am going to give this a try. If it turns out even close to your boxes I would be a happy camper.Hi Bill, I apply Zar polyurethane all the time, but never a stain. As others have said, use a paper towel. I use the blue shop towels that I cut into 1/4. Then I fold until it is about 2" square. I dilute the poly almost 50% with quality mineral spirits. I apply 2-coats a day. No runs and no brush makes and no sanding between coats.
Most woods after a couple coats I apply a heavy coat with a 1" foam brush and go over it with the orbital sander on medium speed using a 400 grit wet / dry sandpaper. This really mades the wood slick and seems to help the grain. I let that dry for 12 hours or so then apply a couple more coats with the towel. Then I use a 500 grit foam pad that fits on the orbital sander that I go over the piece lightly to removed any grit or dust. Then apply the last coat of poly.
Hope this help. Malcolm / Kentucky USA
I have not had good luck with the disposable chip brushes. They tend to lose bristles. Where do you buy yours?I use disposable chip brushes for staining these days, it makes it easy to work stain into crevices on picture frames, which are my most frequent project. I use a prestain as well, which produces better results than applying to bare wood.
I like the paper towel results very well indeed. Use the corners to apply the poly to those tight spots. I also use disposable clear plastic food cups, pour in enough poly for one coat, then squeeze out all the air and close the plastic bottle. I put a lid on the 2 ounce food container if it has to sit more than a minute. Haven't noticed much thickening as a result, but I also have mineral spirits handy. I used a Forstner bit to drill a recess into a short 2x4 to hold the food container, without it, you WILL get a spill.
Sanding picture frames was no fun until I discovered these sanding pads and the new, flexible 3-M sanding sheets. The sheets conform to the shape of the pad, both the U shape and the rounded end and sanding is done in minutes on picture frame stock. Best $10 investment in accessories yet. I generally sand down to 220 grit, with the occasional quick pass with 320 grit to lightly clip off the fuzz that gets raised by the stain. The 3M sheets are really aggressive, almost like card scraping. Next comes a large paint brush to remove the bulk of sawdust, then a very light rub with a waxed cheese cloth to knock off the dust. For picture frames, I'm generally going for a very high gloss, glassy finish. I highly recommend the sanding blocks, which you can get in angled and curved versions from Amazon or woodworking stores..
Dan I tried this thinking it might save me some time but it has cost me considerably more in time and effort than using a stain followed by poly. And yes the product is a Mini-wax stain-poly.Bill; just out of curiosity, why did you go to the stain~poly mix? Were you having difficulties with the stain you were using previously, or was it a time saving thing?
Is the product you're using now a Minwax stain~poly?
*Lips are sealed*Dan I tried this thinking it might save me some time but it has cost me considerably more in time and effort than using a stain followed by poly. And yes the product is a Mini-wax stain-poly.
Got them in bulk from Amazon in batches of 50. I have half inch, one inch and 1.5 inch (although I rarely use the last). I only use them for staining and for padding forms.I have not had good luck with the disposable chip brushes. They tend to lose bristles. Where do you buy yours?