My bookcase construction is done and I've got a coat of stain on it. I'm
planning to brush on several coats of Polyurethane. I've heard, and it makes
sense to me, that I should only apply brush-on finish to horizontal
surfaces. In other words, finish one side, let it dry, turn the piece to the
next side, and repeat. That way, I'll avoid runs and the finish will flow
flat. That sounds great but what happens where the outside or inside edges
meet. I doubt that I can finish the inside sides without getting at least
some finish on the back or front (unless I used an artists brush and even
then, I'm not that steady). The finish that I get on the other surfaces
would create ridges that I would think would be visible and too hard to sand
off without sanding through the stain. I'm sure spraying lacquer would be
ideal but I like the durability of Poly although I'm not about to buy 100
cans of Poly spray either.
I'd be interested in hearing how any of you finish casework with brush-on
Poly. What is your technique? Have you solved this problem?
Well, for each shelf I would do the back, then the top, the sides and
finish with the bottom. Several thin coats are going to flow together well
as long as you don't apply it too thick. You shouldn't get runs with light
Using a spray bomb in an enclosed bookshelf would be messy.
I have use poly for a bookcase however I do remember a not too distant
thread where in someone said they were having a problem of having books
sticking to the shelves months after application. Might be worth a google of
this group. Cheers, JG
I have never gone to that much trouble and I doubt that you would notice any
problems with my finishes.
That said, typically the best way to avoid runs is to put on several and
very light coats with a rag.
Ok, you want to use a brush. Typically the better the brush, the better
Several years ago I started using a brush to apply my finish and in as few
as 2 coats.
Specifically, I use General Finishes Oil based Arm-R-Seal varnish.
I start by wiping on the first coat with a rag followed with a light rub
with 0000 steel wool.
Final coat with a "Name Brand" FOAM brush. Yeah, a foam brush. The foam
rush holds a lot of varnish and lets you complete as much as one to two
square feet of area without having to reload. I prefer the brand brushes
that are sold singley and made by Wooster or Lisdser.
Start at the top and work down. On the sides start at the top of one side
and work down completing that side and moving across after that run starting
at the top and working down again.
As always do a little practice on scrap but I think you will be pleasantly
Vertical surfaces should not be a problem if you use a relatively dry brush
and THIN the poly. It seems counter intuitive but a thin finish will sag
less than a thick one. As far as foam brushes are concerned, they have
limited carrying capacity. The best finishes are put on with a roller (of
all things) followed by tipping off with a foam brush.
I had apprehension just before doing the inside of some drawers. In
actuality if you don't own spraying equipment you're probably gonna run up
to the project and nobodys method wil be better than yours. I used
Helmsnman Spar and a newPurdy brush, three coats I think, and it worked
fine, for all purposes I would say, all things considered. You're not gonna
leave sides out for any sequential pattern. However I went to look a thtem
and I now remember a side-effect of something I did or didn't do. I got
what looked to be bits of sand or grit, air bubbles, or non-adherance spots,
tiny, in the finish. I am sure pretty I would have dipped/saturated the
brush in whatever thinner before applying the poly. I now remember looking
at the spots with a magnifying glass loupe and they were air bubbles. It
was not possible to snad them out to get rid of them completetly. Other
than that I saw no runs just now; nothing to prevent me from saying I would
do all again. But I cannot tell you why I got the bubbles. I could not
brush them out, it probably'd make em worse. I could knock the top off,
and some were worse than others. The gal. can was 6 mos old, and had been
used from the can before, but I have to say it was air, nothing else. A
perfect finish, otherwise. . You may want to research this specific bubble
problem to find out the exact procedure and follow it. It may have been the
quantity of thinner on the brush, or lack of maybe 1% added to the product.
May want to do a test run or two.
I'll second that. I've been using Minwax Wipe-On Poly and it's
been wonderful to work with. I've used some of the other stuff, and
ran into difficulties ranging from runs, to dust and long dry times.
This stuff is easy to work with, and produces a nice finish. And if
you're a fan of New Yankee Workshop, this is something Norm seems to
use on a number of his projects.
If you want to reply via email, change the obvious words to numbers and
I've applied poly to some existing built-ins where applying only to a
horizontal surface is impossible- and they turned out fine. I'd
suggest disposable foam brushes, and multiple thin coats. When you
sand, don't go overboard- 220 or 320 should be coarse enough sandpaper
for the application. Usually what I do is start at the top, then work
down on the sides, and do the bottom last- keep looking back at what
you've finished to make sure it isn't pooling in the corners. If it
is, squeeze out your brush a little on the side of the can, and give
the area a quick once-over to remove the excess poly.
And remember not to shake the can up, or it'll be full of bubbles.
I'll second the recommendation for wipe-on poly. I've never had very
good results brushing on poly - probably because of my technique.
WIping it on with a rag makes the application very easy - foolproof.
BTW, if you already have regular poly, just thin it down a bit to make
a wipe-on poly.
Better still to do that before *every* coat -- and make sure to remove the
dust from sanding, too. A microfiber cloth works great as a tack cloth, and
can be reused over and over and over -- just rinse and allow to dry, or blow
clean with compressed air.
Doug Miller (alphageek at milmac dot com)
you can buy a big piece of cheesecloth, and make your own tack rags as you
need them, just cut a square and add some drops of poly - thats all they
are. Keep it in a ziplock. Whatever you have around - shellac, poly,
varnish. you might be able to use an alternative if necc, like a J-cloth,
if needed but its probably pretty cheap, and worth a trip. Insurance.
I just finished up a pair of built-in bookcases; I was planning to use
spray-on poly all along but at the last minute I wound up going with
Zinser amber shellac, wiped on. Came out very nice, and was easy to
apply as long as you work fast and have plenty of lint-free rags. I
love that stuff now - looking for excuses to put it on anything. There
must be a saying, "once you shellac you'll never go back"...
I've just been using the Finish Factor brand bag of wiping cloths from
Lowes - claims to be 'all cotton, t-shirt material, lint-free'. They
do a decent enough job. A friend of mine always has a roll of real
lint-free cloth that he uses to clean his gun barrels - not sure where
he gets them, but that's probably the real McCoy - the texture is
different, sort of pitted like a cloth paper towel. He's pretty fussy
about those firearms, more so than I am about my weekend warrior wood
Cut it 50% with mineral spirits, wipe on with a rag, keeping
the surface wet with finish for 5 - 10 minutes. Wipe off
until the surface feels dry to the touch. Scuff with grey
Scotchbrite. Repeat for 3 - 4 coats. A dash of linseed
or tung oil added to the varnish / thinner mix helps to
keep the rag from sticking to partially dried finish.
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