Getting good results with brushed poly
davidmeiland
| Posted in Construction Techniques on
I’ve got a large table top to finish, using oil-based clear poly. It’s new, white ash about 44 x 105, dead flat, sanded to 220. Any tips on getting a good smooth finish when brushing? Don’t know if penetrol or another additive might work (used penetrol with paint but not with varnish before) or if there are other tricks. Spraying this thing is completely and totally out of the question. Planning on 3 coats, careful sanding between, etc.
Replies
I have had great results with a foam brush using water borne poly. They're good for large flat areas as it goes fast so you keep a wet edge. Never tried with oil based though.
Stay away from where you already applied. Let it flatten out on its own.
Don't use it out of the can, put it in a smaller container and throw it away after each coat. This keeps the remainder from getting contaminated.
What are you sanding with? Steel wool, scotch brite? Sandpaper?
Spraying is not necessary either.
I don't do that much furniture but I did learn how to make furniture look like furniture.
I read an excellent book on finishing (I think the author's name was Flexner) and the mistake everyone makes is not "finishing the finish".
What you need to do is let the finish coat dry - really dry, and then come back and hit it with some really fine abrasive. You can use loose abrasive like rottenstone or pumice or just really fine sandpaper and by really fine I mean like 1500 or 2000 grit.
I did a maple bookcase for my daughter and used shellac for the top coat and then did as I described above and it came out nicer than any piece of furniture I ever store bought. Like smoother than your car after polishing and a coat of wax (yes, polishing and waxing are 2 totally different things).
Talk to the people over at Knots, they live for this kind of stuff.
Good luck.
"Talk to the people over at Knots, they live for this kind of stuff."Yes indeedy! This is a crossover subject.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
Interesting about finishing the finish. Wear and tear on newly finished floors must do that, as any imperfections seem to disappear during the first few weeks. Of course over time the process reverses itself.
Just a thought.
Are small brush strokes a bad thing? I've found that smaller brush strokes look good to me.
A dead flat surface has it's place but it's not always what i want.
When I see small uniform brush strokes i know it was hand applied by someone who knew how to paint. It's more of a hand made look to me.
Will Rogers
Edit: Sorry - I should read more carefully. You're using oil based poly. You might want to try a lambswool applicator. For me, using a wide applicator helped to get a level, unmarked finish. Sanding between coats made it smooth.
I've had good luck with water based poly on large surfaces using a flat paint pad.
Edited 6/24/2009 2:43 pm ET by BobI
David,
I rag the last coat on. Sand 3rd coat to 400. Mix 50/50 poly and thinner. Brush this on and wipe off with a cotton rag that's damp with thinner. Comes out slick as owl poop.
KK
I used the cheap foam brush applicators to apply poly to three sets of double birch slab doors. I did not thin it with anything, and they came out well. For three coats I would get three of the applicators, and throw them out after each coat. Also, don't put too much on each coat. I used steel wool between coats.
Hope that helps.
I second foam but recommend the more expensive Wooster foam ones they have in Lowes. I have never had one of them come apart on me and are actually cleanable/reuseableFor those who have fought for it Freedom has a flavor the protected will never know.
Thin first coat. sand at least 220 between coats and vacumn and tack clothe each time. Clean brush of course, and don't overwork the brush. Be absolutely sure each coat is cured before doing next coat. Too quick and no O2 gets to it to cure hard and that middle coat will always be a gel - soft.
Myself - I;d rather do a table with waterlox rubbed in.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
Thin your finish a bit; you can thin it 50/50, like someone said, and apply it as a wipe-on, or thin it just enough to brush easily- maybe 10-15% or so. Experiment on a test piece to see what feels comfortable. And be sure to keep track of how much you dilute the poly. I sometimes forget, and its a PITA to figure it out again.
And I like foam brushes for this kind of work. They apply the poly very evenly, and better yet, you just throw them out when you're done. No clean up.
>Thin your finish a bit; you can thin it 50/50
I agree with the first part, but 50/50 (mineral spirits) would be way too thin; you'd probably need a dozen or more coats with that cut.
>thin it just enough to brush easily- maybe 10-15% or so
Now you're talking. Put it in a glass jar, and stir in a very little at a time. It doesn't take much to change the consistency, but you'll see it change quickly when you hit the right point. I usually use a disposable shop rag folded so none of the edges are showing, then really soak it in the "wiping varnish" as it would then be called. You'll need more coats, but it smooths out nicely, so you won't have much sanding in between; just to remove the dust specks and too scuff it up a bit.
---mike...
p.s. and go ask at Knots :-)
My approach:
Thin out the first coat anywhere from 25% (1 part thinner, 3 parts finish) to 50%. Make sure the table top is laying dead flat. Shine an incandescent light on it at a low angle on the far side of your work area.
Use a nice 2" to 3" wide badger brush. They aren't cheap. They work better.
Dip the brush into the thinner (min. spirits), then LIGHTLY dab it against the thinning can to drain the excess. This fills the inner brush with solvent, which will "push" finish off the brush end. It'll also make it a lot easier to clean later.
Don't work out of the parent can, pour and mix (even the 100% stuff) into a separate container you can hold with one hand.
Dip the brush into the finish, at least 2" deep. Pull the brush out, tilt it and let the excess drain out of the brush. Don't shake, don't scrape it against the can, don't squeeze it: just let the excess drain off until it drips.
Try to go in full length strokes, one end of the table to the other. If there isn't enough finish on the brush to make it the whole way, then here's a trick. Start in the middle, and stroke the coat down to the end of the table. For example, start at the 52.5" mark of your table, and lay finish down to the end. The finish should readily flow out of the end of the brush at first, you'll have to push a little harder towards the end of the row.
Reload the brush. Now start from the end of the table (the part that didn't get finish) and lay out the coat until you meet up with the part you already put down. Continue the stroke all the way to the end - this will even out the layer between the two. Here's a lame attempt at visually explaining (0 = no finish, x = finish)
Unfinished tabletop:
0000000000000000000000000
0000000000000000000000000
0000000000000000000000000
First pass:
0000000000000XXXXXXXXXXXX
0000000000000000000000000
0000000000000000000000000
Second pass:
XXXXXXXXXXXXXXXXXXXXXXXXX
0000000000000000000000000
0000000000000000000000000
Successive rows should barely overlap, maybe 0.5" or so.
Tip off each row immediately after you've laid down the full coat. This means lightly scrape the brush tip along at almost a 90 degree angle. This again evens out the brush stroke.
For big pieces, I alternate the pattern as I lay successive coats. With careful sanding, you'll get more uniform layering.
Ash has fairly large pores. I'd consider filling them first if you want a real uniform flat look to the finish. Otherwise you may need to sand and finish 5 or six coats to get the same point. Depending on the effect you want, this might not be a concern, I'm just pointing it out.
-t