Hello, all. I’m ready to finish a cabinet I built from birch plywood and faced with red oak. I also added pine lipping to the ply doors because it was available in 1/2 X 3/4 and fit the edges perfectly. I realize that my red mahogany stain is going to be uneven.. but that’s okay.. I think the overall effect might be nice. What concerns me is this.. the last time I stained a similar project, (desks), the stain raised nibs or nap or whatever you call it, in the plywood. When I tried to sand these out, (Minwax instructions to the contrary), it lightened the stain in some places and I ended up restaining and living with the results; a surface that is tactily unpleasing. I did steel wool some pasted wax over the poly topcoat and that improved things somewhat.
Anticipating the raised wood fibers when I apply the stain.. I’m thinking this time about using 400 to 600 wet/dry paper or maybe 0000 steel wool once the stain dries.. and before everything is cast in stone by the topcoat. Is this a reasonable idea? Thanks..
bill
Replies
Bill - once the stain is completely dry - go ahead and apply your first clear coat. If you're using a wiping finish, apply 3 coats, one after the other as soon as the previous coat is dry and firm to the touch. Then sand lightly with 220 or 320 grit to remove the dust nibs.
The finish will lock in the raised wood fibers and dust nibs and you can cut the exposed ends off with a light sanding without removing any of the stain.
Paul
F'burg, VA
Thanks, Paul. One more question. I'm using Minwax fast drying polyurathane as a topcoat. Should I use it straight.. or dilute it with mineral spirits? I'm thinking that since it's "fast drying" it may already be diluted. It is oil based. Thanks for the tip on sanding after the topcoat.
bill
Bill - You can thin the Minwax to get the consistency you like best. If you're using a wiping technique, try it straight out of the can on a test scrap (the larger the better) and see how it works. I haven't tried it straight out of the can, but it might work fine. When I used it, I was using it as a sealer and thinned it so it would cover more area with a thin film. A thinned coat was dry in an hour or two, depending on the weather.
In the previous post, I should have said to let the finish dry overnight before sanding. Give the finish a chance to cure before sanding. Sand like you are dusting - long, light strokes with the grain to remove the roughest texture. Remove the sanding dust and wipe on more coats. If the finish is still rough/lumpy after the second set of wipe-on coats, sand a little more aggressively to remove the imperfections. Then wipe on the final coat.
Paul
F'burg, VA
Thanks for the clarification, Paul.. I thought you meant to sand only after the third coat of poly. I think I've got it now. Thanks again.
bill
Bill,
Another alternative. I hit my sanded piece with a wet rag before applying stain and let dry...take off nibs and hairs with 400 grit or a scraper. I may do that up to three times before the stain and finishes.
Yeah, as I sanded today.. and thought I had a smooth surface, (by running my hand across it), I'd wipe the surface with a cloth to remove the dust.. and the cloth would raise hairs. I finally moved to 180 grit by hand and removed the hair. Now I'm probably half way or better through the birch veneer and worried about doing anything more than a very light sanding. Man, I love and hate plywood!
bill
Bill,
You might be working too hard....except for the saw marks, I usually start with 220 grit when sanding birch or oak ply...and often end there too. I try to erase pencil marks rather than sand those.
Between coats, as Paul suggested, very light strokes with 220 or higher. Quite frankly, I like the scraper because it does not create any dust and it removes the nibs.
I've used the steel wool and wax routine with success, but recently I used parrifin oil and 400 grit to rub out...wow, far superior..again fairly light strokes. I'll let it all harden a week or so and then wax. good luck
Others may be clear, but I'm not sure if you meant apply 3 coats without sanding, then wait overnight and sand, or you meant sand between each coat.
If you use the wipe-on technique, apply three coats - each coat just as soon as the previous coat is dry to the touch. Let these 3 coats dry overnight, sand lightly to smooth, wipe-on 3 more. Next day sand smooth, wipe-on the last coat.
Just a way to build the film faster with the wipe-on technique. With the finish thinned enough to wipe, each "coat" is very thin and the "quick 3" ends up being about the same as one coat applied by brush.
HTHPaul
F'burg, VA
Thanks, that's what I thought you meant.
BG.. sorry to be so late getting back to you but I couldn't get this website to come up yesterday for some reason.
I think you're right. Starting with 100 may have created more problems than it solved. I just completed the finish on my closed door cabinet today and am very happy with the results.. although it's not perfect by any means. I sanded with 220, lightly, by hand, after coats one and two. The topcoat isn't dry yet so I can't touch it.. but it felt great after the sanding.. and look great right now. Man, I can't tell you how much I picked up about sanding, staining and topcoating from my first project. I have a much better technique now, thanks to a little experience.. and lots of help from my friends, like you, on knots. Thanks, BG.
bill
Hi Paul, I was cruising threads looking for an answer to a problem and you seemed like the person with the answer! Hope you can help.
I am a novice so this may be a simple one. I am using a spray polyurethane, and keep getting drips. I sand and spray lightly but keep getting the drips. Can I "rub them out" with mineral spirits to get an even coat? Or should I skip the spray and sand again and go back to a can and brush? What about a good brushing technique?
Thanks for your help,
Brian McGinnis
Hi Brian - runs and sags in a sprayed finish can be removed with a scraper or razor blade; sanding usually cuts through the finish surrounding the run or sag before it's leveled out. I use a single edge razor blade to carefully scrape the run/sag level. Then sand the entire surface with very fine paper and spray another coat to even the sheen. If you use Mirka Abralon on a random orbit sander to do the between coat sanding it will help level the remains of the run/sag.
Try working on your spray technique a little to avoid the runs. You may have the sprayer (can or gun) too close to the surface. With a spray can, stay about 5" from the surface. With and HVLP spray gun stay 6" - 8" away. With a conventional spray gun stay 10" away. A couple light coats works better than a single heavy coat. With some practice, you can get rid of the runs and will find spraying is fast and easy.
For brushing, technique is the critical factor. There's some tips at this link - Brushing Varnish. An alternate option is to thin the varnish and use the wipe-on technique. Wiping the finish leaves thinner coats, so you need to apply extra coats to build a film; but it's easy to do.
Paul
Thanks Paul, Very helpful.
One of the causes of running in varnish at this time of year is applying it when it is too cold. Be sure the wood, finish and the air temperature is above 65 degrees.
Brian,
If you're working on a large piece, and can't put the finish on it while it is laying flat, turn it upside down before you start spraying. Nobody expects a drip to run upward, and the fattest part of the drip will be at the top, so there won't be a shadow below it, as there would be if it dripped downwards.
The other folks are right, too, about working on your technique. I use a compressor powered el-cheapo HVLP gun, spraying water borne poly, and I wiped off more than I left on the first few pieces I sprayed with it.
Hope this helps.
Enery
Thanks Enery, appreciate the help. Brian
I wipe distilled water on the wood and sand with fine sandpaper a couple of times.....and then dye (transtint) and then shellac before I sand.....glass-like finish
lp
Most of my project is constructed of birch ply. Can I safely put water on it? Thanks..
bill
Larry, you and BG have both given me an excellent and much appreciated tip with regards to raising the hairs with a wet rag.. and then sanding them off before staining and topcoating. It was, after all, the stain that raised the hairs.. so why not get them buggers up with water BEFORE finishing! I still have shelves and bridges to add to my office build out.. and will definitely add this technique to my finish in the future. Hey, I'm beginning to think this finishing thing isn't so bad after all. Thanks again.
bill
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