Adventures in grain filling

[Robert Engel]

My first time doing this, and I can't help but wonder if I'm doing something wrong.

I'm applying a fairly liberal coat (AquaCoat) and have tried spreading various ways, but the all leave small grooves in the filler. I'm sanding with 320 using both foam backed pads, and a hard block but by the time I sand the grooves out, I feel I'm back to square one.

I'm also noticing hazy patches when I'm done. The filler is going over a sanded wb poly top coat.

On top of that, I managed to sand through a couple places.

At this point, the 3rd coat, I'm going to sand it and give up but I'm concerned about what its going to look like after the top coat. Planning to use a satin conversion varnish.


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[Prashun Patel]

I have the same problems. IMHO, leaving too much on is way more detrimental than taking too much off.

I use Crystalac, but it yields the same issues. Here's what I found works for me:

Wipe it on with a sponge in small circles. Rub it in. Wipe cross ways with the scraper (i'd use a credit card or plastic knife...). Then wipe WITH the grain again with a shop towel. Don't be afraid about pulling it out of the pores.

A couple hours later, sand back with 220 or 320.

I am fairly new to grain filling, but at this stage of my development, I find it easier not to rely on grain filler to get me all the way to flat and level. I expect pock marks and expect to have to build up a few top coat layers, and repeatedly level them until a flat surface is achieved.

In my experience, the 'scratches' will reduce the higher your coats go. But the blotches don't cover well - especially if you are coloring and or doing a gloss topcoat....

[Phil Mueller]

I have used both oil and water based grain fillers. I find both work, but prefer the water based (Timbermate, Wunderfill), as they dry quickly. I have not used crystalac. I sand the wood to 220, then seal it with SealCoat Shellac. I apply the filler at about the consistency of thinish mayonnaise. I apply it with the grain and crossing the grain...let it set up a little, then remove the excess across the grain. I use a plastic bondo spreader thing.

I then sand with 400 until I just get to the wood surface. I seal that with SealCoat (spray can). Once dry, I lightly sand with 400, then assess the fill. It’s not unusual on deep grain wood that two or three applications are necessary.

It adds considerable time to the finish schedule, but I think it’s worth it for some projects...especially if I’m looking for a gloss finish.

Here is a table top I’m working on. The main field is Rosewood veneer and it was quite open grained. This took three filler applications.

I also pre-filled the curly cherry border prior to glueing up the veneer.

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[Robert Engel]

I’m filling this after finishing. I think that’s made it more difficult. I’ve got 3 coats of finish on it now and looks like it will be alright with some rubbing out.

Next time, I’ll do it when I’m supposed to.

The table is stunning!

[Stan Calow]

Even though the company website info says you can, the instructions do say to apply after stain, implying before any finish.

[Prashun Patel]

For future ref, filling after finishing means filler can get pulled out easier during the application. The pores get rounded over. On the other hand filling before finishing means it’s harder to sand.

Waterbased filler dries very fast. I am still learning too, but am finding success by sealing lightly before and working in small sections, applying and wiping off quickly.

[Jim Becker]

The nature of what you are coloring with will affect whether you apply the filler. Some stains have a binder that effectively seals the wood which makes using filler immediately easier. If you use a dye, you may want to do a coat of finish or wax-free shellac first to seal before using the filler. It's best to test the combinations on scrap to determine what works best. Filler is also best put on thin and with multiple applications, lightly abrading back until things are filled. Obviously, you don't want to sand back so far that you cut through whatever sealed the wood and color, so by using very light applications of the filler, you can work your way up to smooth as a...with only very light abrasion necessary to remove the excess filler.