Sealing Pores in Sapele with Shellac - What am I doing wrong?

[Alan Lightstone]

Tried an approach to seal the grain / pores in a sapele table top by using multiple coats of 1# cut dewaxed shellac, then sanding off all but the shellac in the pores. Found the approach here:
http://www.hardwoodlumberandmore.com/Articles/ArticleViewPage/tabid/75/ArticleId/17/Grain-Filling-with-Shellac.aspx

Not working out so well. I'm trying to sand down to the bare wood with my Festool 150/3 and 150 and 180 grit, and the sander is constantly catching/jumping on shellac glop. Also not easily getting down to the bare wood. What am I doing wrong? Did I put on too much shellac? Should I be wet sanding by hand instead of power sanding?

I'm at the stage now that I traded a very smoothly sanded table top for its present condition of a bumpy poorly sanded one.

What is my best approach now?

[glenn bradley]

My first reaction is "put away the power sander". That being said; if your sander is catching my first guess is too much shellac before sanding -or- not letting the shellac dry completely before sanding (or that you are power sanding at this stage). One wiped on coat of 1lb should dry in 30 - 60 minutes. If you have multiple coats on, put on some gloves, get a bunch of rags or paper towels (I prefer paper towels), soak them in DNA and scrub, scrub, scrub that shellac off. Change rags often so as not to reapply what you are trying to remove. I have committed the 'too much shellac sin" and recovered nicely by scrubbing it back off and starting over. ;-)

[Alan Lightstone]

Just tried the DNA/scrub with paper towels. Did wonders. Then power sander followed by hand sanding worked fine. Not sure how well the pores are filled now, though.

A little scared to try more coats of shellac to get the deeper pores.

[glenn bradley]

I understand the fear-factor after just recovering; BTDT ;). There are as many preferred ways to apply shellac as there are members I imagine. I use a wad of cheesecloth about the size of a golf ball wrapped with an old section of t-shirt. Make sure the face that applys the shellac to the surface is wrinkle-free.

I squirt some 1lb shellac onto the pad with a squeeze bottle (like a mustard bottle). I apply in light continuos stroles with the grain (usually). The main lesson to learn about shellac is that once you have made a pass, do not go back over that spot. The shellac dries too fast and you will leave tracks. This, thin coats and patience will prevail :).

Now having said all that; I really don't find shellac to be a good filler, although I have done it. A great trick out of some book . . . if you are going to use and oil; like BLO, Watco or some such . . . Plaster of paris applied to bare wood as a filler, sand flush, when the oil hits it it goes translucent. Works well on things like red oak but, woods with deeper figure (walnut, cherry, maple) do not fair so well.

[Alan Lightstone]

A great trick out of some book . . . if you are going to use and oil; like BLO, Watco or some such . . . Plater of paris applied to bare wood as a filler, sand flush, when the oil hits it it goes translucent. Works well on things like red oak but, woods with deeper figure (walnut, cherry, maple) do not fair so well.

Pg 187 of Jeff Jewitt's Finishing Book

[Scott Holmes]

When I fill pores with shellac; I use a 2# or 3# cut and give it a heavy wet coat. Let it dry and then scrape or sand WITH A SANDING BLOCK back to leave the shellac in the pores only. The technique you linked is an excellent and is essentially the same that I use to fill with shellac...

[Alan Lightstone]

I think my initial problem was coating with several wet coats of 2# cut. I think it just got too thick. The problem seems to be you need it thick enough to fill the pores, yet not too thick on the wood surrounding the pores.

Scott, do you sand after every coat?

[Tim Mahoney]

The best method I found was the french polish method as described at the Milburnguitars.com site. I followed his directions on my acoustic guitar and was very happy with the results. After 2 sessions of applying a 2lb cut, I rubbed in 4f pumice only using alchohol. Don't use any more shellac until you have the pores filled. It may take more than one session.

[Scott Holmes]

I sand when I think the pores are filled sometimes after one or 2 coats sometimes more; depends on the wood. If the wood is not filled but I see the shellac starting to get thick I will usually use a pad with DNA and wipe the shellac to move it around and fill the pores. Similar to what Tim said below. I personally don't like the French polish method because I don't like the look of pumice in the pores.

[Ken Fitzgerald]

For the record.....I stumbled onto the DNA with paper towels to remove excess dewaxed shellac. Then later found I was able to level out / remove excess brushing lacquer using paper towels and lacquer thinner. Who would have thought solvents could rescue you like that?

[Scott Holmes]

Shellac and lacquer (nitro cellulose,non-cat) are what I call "evaporative" finishes once the solvent evaporates all that's left is the finish. Add the sovent again and you redissolve the finish.

Varnish is a reactive finish, once the THINNER evaporates then a chemical reaction takes place. add thinner after the reaction has taken place and nothing happens.

[Alan Lightstone]

For grins I sealed the bottom of the table top with the shellac sanding method, and the top with the oil/varnish sanding slurry method.

The shellac method was much more of a pain to do (probably just because I put on too much shellac), but initially it looks like it filled the pores better than the slurry.

After I finish putting on all the Waterlox coats and they dry, I'll post some pictures of both sides (although I'm not sure photography will show the difference. Or should I say MY photography ;) )

I'm really interested in trying the Plaster-of-Paris method. It sounds like it would be far quicker, plus look quite good. I'll probably try that on a sample board at some point and post that too.

Every time I do a new project I choose a different method of construction and finishing. That way I'll keep learning. Fortunately, each project seems to get better and better.

[glenn bradley]

When I fill pores with shellac; I use a 2# or 3# cut and give it a heavy wet coat. Let it dry and then scrape or sand WITH A SANDING BLOCK back to leave the shellac in the pores only. The technique you linked is an excellent and is essentially the same that I use to fill with shellac...

And the learning never ends :). I assume my dissatisfaction with filling pores with shellac comes from not using a thicker mix. I was trying to sneak up on it. I will give a 2 or 3 pound cut a try next time the opportunity comes along. Thanks to Scott, as always.

[Alan Lightstone]

One thing I'm confused about. Can you use paste filler (e.g. Sherwin Williams or Pore-o-Pac) under an oil/varnish finish like Waterlox? If so, what's the order of application (dying wood, +/- seal coat with shellac, paste filler, Oil/Varnish)?

If not, what fillers besides oil/varnish slush, shellac, and plaster-of-paris are compatible with an oil/varnish finish?

[Howard Acheson]

>>>> under an oil/varnish finish like Waterlox?

Waterlox Original is a varnish, not an oil/varnish. Vanishes are made with a resin and a drying oil. In Waterlox, the resin is phenolic and the drying oil is tung oil. Once they are heated together they combine to make a new compound called "varnish". Oil varnishes are products like Watco or Minwax Tung Oil Finish.

To answer your question, you can apply Waterlox Original varnish over a pore filler. Follow the directions on the pore filler but the usual procedure is to first color the wood, seal the coloring with a 1# cut of shellac, then the pore filler and finish off with the Waterlox varnish.

However, as you have never done this before, don't make your project your learning curve. Alway test and try out your complete finishing schedule on scrap from your project. Only when you are happy with your test results should you move on to the real thing.

[Alan Lightstone]

Thanks, Howie. My project has the shellac filler on the bottom of the table top, and the slurry on the top, so both low risk procedures. I will definitely test the paste fillers on scrap.