Sprayable grain fillers

      Sources and application techniques for sprayable grain filling products. November 29, 2000

Is there a spray-applied grain filler I can use on oak, etc. that takes stain or can be tinted?

Forum Responses
Hood Finishing has a spray type grain filler. You can order a catalog from them at http://www.hoodfinishing.com

Hood does have a lacquer based sprayable grain filler that will do just what you need. But this cannot be used with precatalyzed and post-catalyzed topcoats.

There are other sprayable fillers available from ICA, Ilva, Chemcraft, etc. These are catalyzed polyurethanes or polyester fillers. You have to read the spec sheets for each product to see what you would use to color it.

There is a filler from M. L. Campbell called A.C. Sealer (A.C. = acid catalyzed). The difference between this filler and let's say one of those high tech fillers from ICA is that the M. L. Campbell is sprayed on and sanded off so that it just sits in the grain pores of the wood, not on the wood flats. The ICA filler sits in the grain and is built up on top of the wood as well. The M. L. Campbell filler has a pot life of 8 hours (less if it's real hot). The ICA fillers have very short pot lifes like what you would find in automobile coatings.

If you are doing a nitrocellulose finish, try the Hood filler. You can add their base concentrates (these are paste colorants) or dye stains to it to get color. But then this will also act as a toner.

How about doing your finish, applying a glaze coat to color the pores, and then applying one of these fillers on top of that glaze coat (watch for incompatibilities!).

The ICA filler you speak of also is sanded to become a full filled finish. So, if I understand this, you spray on the A.C. Sealer and then sand back down to the wood? Cutting all sealer off the flake of the wood? What about stains or dyes if used? Or is this product so thin it pools into the pore? If so what about vertical surfaces?
I have not used this product yet and would love to test it. When I do full fill I run for the polyester and urethanes. Or the old paste wood filler!

Bob Niemeyer, forum technical advisor

From the original questioner:
I have found a water born filler called woodwise. Its primary use is on hardwood floors and it comes in every possible color and takes universal colorants. It sands very well, and is put on with a squeegee.

Using M. L. Campbell's A.C. Sealer requires that you pay close attention to how much you sand. Let's say that you want to sand down just to where your stain coats are, leaving as little build of the sealer on the flats of the wood as possible. So you are sanding almost all the sealer off, but not 100%.

One question that comes to mind with this product and many others is shrink back of the film (shrinkage). What today looks like a finish with a 100% fill could look like something 90% filled over the course of a few months.

That shrinking back of the filler is one question that you need to ask each finish manufacturer. Open pore, semi-fill, and full fill are three very different things.

Sounds like the same process as the ICA urethanes to get full fill.

Bob Niemeyer, forum technical advisor

In using the ICA urethanes, can't you build a thick coat on the wood with them as well, and then continue with your topcoating? Also, I was under the impression that the ICA urethane and polyester could be used as a topcoat in itself. Am I thinking of a different ICA product? I have heard about them but I have not used them.

The M. L. Campbell product can only be used as a filler, even though they call it a sealer (A.C. Sealer). It is not meant to add much to the total dry film thickness.

Back to ICA. I know that their polyester filler is not very reversible at all. But what about the strippability of the ICA urethane filler? And if you can use the urethane for a topcoat, how well does it polish? If not, the polishing question is moot.

ICA has several sealers to fill with and yes you can put high millage with no problems or clouding of the finish, plus it sands like butter! As for topcoats, there are many to choose from, flat to a high gloss of >95 deg sheen off the gun. The high gloss polishes very well, as that is what it is made for. Also it will strip with MC based strippers. As for the polyester, it's very easy to work with and also sands very nice and best of all almost nill shrinkage. Performance of both products is outstanding. Just think--no acid fumes to breathe, no burning eyes from the varnish fumes, no worry of millage and best of all no formaldehyde (isn't that what they pump in dead people?).

Bob Niemeyer, forum technical advisor

Formaldehyde? If you never want to age, then formaldehyde is the way to go. Frogs float in it. OK, the frogs are dead. And the age stopping process also kills you, but there are tradeoffs in everything, especially in the finishes that we use and the ways we apply them.

It sounds to me that the ICA filler has more benefits than does the M. L. Campbell "A.C. Sealer" filler. For one, you can build the ICA on top of the wood; you cannot do that with the M. L. Campbell. There is no shinkage of the film with the ICA filler; a finisher whom I know tells me that there is shrinkage with the M. L. Campbell product, yet it took several months for the shrinkback to exhibit itself. Feh!

The downsides of the ICA filler is the cost is much higher. The potlife is significantly shorter. The mixing is more of a pain (resin + hardner + reducer).

But for ease of application, reversability, and performance, ICA is a winner. The cost of the material is cheaper in the long run if you are worried about possible callbacks to fix (onsite, nonetheless!) a shrunken film finish that was supposed to be a full fill.

Are there other products from other suppliers that are comparable to the ICA fillers? What about Ilva Polimeri? Chemcraft/Sadolin? Seagrave Coatings? Others?

What is the specific ICA product to which you are refering (product number please)? Is it actually a "filler" (i.e. designed specifically for pore filling) or is it a polyurethane sealer? I ask because we have customers in Latin America who are always looking for full filled finishes and have real difficulties achieving them with the porous, tropical woods that they use. Can the ICA product be used in exterior environments (e.g. doors, window frames, etc.)?

You can use a polyester sealer or a polyurethane sealer to fill the pore but the polyester has high solids and will do the job in one coat or two coats compared to the polyurethane, which has lower solids and dries quicker and can be ready to sand sooner. Seagrave polyester sealer has a pot life of 1-2 hours depending on temperature, but you will probably have to wait overnight to sand. More information would be at their website, www.seagravecoatings.com. It should be stressed that you can't just top coat these materials with anything you want. If you use a strong acid cure varnish over these sealers, you could cause a reaction with the zinc sterate used in the sealer, creating the look of white spots or blooming. Therefore, the manufacturers directions should be followed.

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