Grain Filler

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Forum topic by Chris Dehmer posted 06-06-2009 05:11 PM 2269 views 0 times favorited 13 replies Add to Favorites Watch
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Chris Dehmer

25 posts in 3576 days

06-06-2009 05:11 PM

I have a Walnut table top that I would like to add a grain filler to. Has anyone ever applied a grain filler to a project that already has finish on it? I can add more finish on top of the filler but would really prefer not to have to remove all of the finish that is on it. The finish that is on it is water based lacquer. Anyone have success with this?

-- Chris,Atlanta Georgia,

13 replies so far

View tomakazi's profile


686 posts in 3521 days

#1 posted 06-06-2009 06:17 PM

Hey Chris. I’ve never done this and I’m no finishing expert, but I would think that some grain fillers wouldn’t bond to the finish like they’ll bond to wood. Some sort of clear epoxy maybe? I don’t know.Let me know what you end up doing.


-- I didn't go to college, I was too busy learning stuff - Ted Nugent

View kolwdwrkr's profile


2821 posts in 3829 days

#2 posted 06-06-2009 06:30 PM

Your best bet would be to fill the pores with finish. Spray the same finish you’ve already applied, sanding very thouroughly between coats to keep from excessive build up. The finish will fill the poors and give you a glossier finish. You’d basically be flat sanding each additional coat off until the pores are filled.

-- ~ Inspiring those who inspire me ~

View Douglas Bordner's profile

Douglas Bordner

4035 posts in 4302 days

#3 posted 06-06-2009 06:35 PM

Here is a link to Karson’s blog about using rottenstone and pumice as grain filler. You can also prep your stock with sanding to P320 and then wet sand in several coats of Danish Oil or BLO with wet-dry 400 on the first coat, 600 on the second. This will leave your open grain filled with a mix of abrasive and sanding dust of the same species as your workpiece and it will be silky smooth. After the finish cures you can leave as is or seal with dewaxed shellac and topcoat with virtually any clearcoat finish. If you use oil-base varnish (poly, urethane or alkyd) you can skip the shellac sealcoat.

-- "Bordnerizing" perfectly good lumber for over a decade.

View CharlieM1958's profile


16281 posts in 4457 days

#4 posted 06-06-2009 06:35 PM

What Keith (kolwdwrkr) said.

-- Charlie M. "Woodworking - patience = firewood"

View kolwdwrkr's profile


2821 posts in 3829 days

#5 posted 06-06-2009 06:47 PM

Don’t try filling the pores with any type of foreign matter. When you sand your finish it will make white dust. The white dust stays white. You need to sand the existing finish and clean it with air and a tack cloth to get all the dust off of it and then continue with another coat. I don’t agree with using rottenstone or pumice as grain filler simply because it is an abrasive and doesn’t have any binders. Anything that can be blown off your project when dry should be blown off your project when dry. Topcoating a foreign matter will in most cases cause fish eye, air bubbles, or blushing, along with adhesion problems.
If you want to see what works do an adhesion test. To do this take a sample board and get it to the point your project is now. Then from there try different methods to fill the pores and then finish. Once you are satisfied and the project is dry and usable take a utility knife and cut an asterics (*) into it. Put tape over the asteric and press firmly. If finish comes off when the tape is pulled you lose, if the tape is clean it worked.

-- ~ Inspiring those who inspire me ~

View Chris Wright's profile

Chris Wright

540 posts in 3720 days

#6 posted 06-06-2009 07:40 PM

I’m with Kolwdwrker, applying more finish and sanding in between coats is the best way to fill the grain. Ideally you would want to fill the grain before a finish is applied, I’ve have really good results with several coats of a spray sanding sealer, sanding between coats then applying the finish. Just an FYI, stripping the old finish off can be done very easily (if you don’t have a stain on the top). You can use some thick felt, cut to the shape of the top saturated with lacquer thinner and just let it sit. If you don’t have or don’t want to get felt, a pile of saw dust works just as well. The old finish should scrape off once it sits for a little bit, then with a quick pass with your palm sander and your ready for a new finish.

-- "At its best, life is completely unpredictable." - Christopher Walken

View Raymondz's profile


64 posts in 3852 days

#7 posted 06-06-2009 07:47 PM

Like they said, build up the finish.

If you didn’t add color the walnut in any way, you could sand to the bare wood every time. This would take less coats since you only have to built it up to the surface of the wood and not the finish already there.

-- - Ray

View Chris Dehmer's profile

Chris Dehmer

25 posts in 3576 days

#8 posted 06-06-2009 07:50 PM

I did have to color this piece and will have to go with the multiple coats of finish. I’ll probably use a card scraper instead of sand paper.

Thanks to all.

-- Chris,Atlanta Georgia,

View kolwdwrkr's profile


2821 posts in 3829 days

#9 posted 06-06-2009 08:11 PM

The card scraper may leave deep scratches. I wouldn’t suggest that method. You don’t need to sand the existing finish off. Just sand to the existing finish.

-- ~ Inspiring those who inspire me ~

View Karson's profile


35153 posts in 4639 days

#10 posted 06-06-2009 08:26 PM

Keith: I guess that you didn’t read my blog on rottonstone and pumice as grain fillers. The binder in my case is BLO or Danish Oil. That process is a published way to fill pores, it was not my invention, I learned it fron Jeff Jewit in his class on finishing.

But I wouldn’t want to put a filler on top of as existing finish. I’ve used finish many times as the filler and that is what French Polish really does. It fills the pores with shellac and then you sand the surface down until all places are level.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Appomattox Virginia †

View kolwdwrkr's profile


2821 posts in 3829 days

#11 posted 06-06-2009 08:34 PM

Karson, I can understand it better if it is mixed with a binder.

-- ~ Inspiring those who inspire me ~

View Chris Dehmer's profile

Chris Dehmer

25 posts in 3576 days

#12 posted 06-06-2009 08:52 PM

I have a card scraper that I rounded the corners on and use it all the time between coats on large flat surfaces. It works great with a light touch.

-- Chris,Atlanta Georgia,

View BTKS's profile


1989 posts in 3703 days

#13 posted 06-07-2009 10:46 PM

All above; thanks for the primer in walnut or open grain woods. I’ve got a stack just aching to be cut up. Now it can be finished decently.

-- "Man's ingenuity has outrun his intelligence" (Joseph Wood Krutch)

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