Pumice and Rottenstone as wood filler.
When you go through the catalogs and look at all of the finished that are available, you will not see this tip.
They sell you Pumice and Rottenstone to be used as a buffing and polishing agent to bring up a gloss on the surface, but no one tells you about using it as wood filler. The interesting thing about Pumice is it is basically transparent so if you use it as wood filler it doesn’t contribute any different colors to the wood that it’s being used on. The Mfg version of Oak wood filler might not be the same shade that your board is, so what happens is you fill the pores of you wood with a different color wood. Maybe this is what you want, maybe it isn’t. The Rottenstone on the other hand is black wood filler. It is great for use on Walnut and other dark porous woods. It makes the grain lines visible. Remember you don’t use wood filler on cherry or maple because the pores of the wood are not present. Where red Oak and walnut have a porous surface. If you want a smooth gloss surface you want to fill all of the pores.
I took a finishing class taught by Jeff Jewitt and this was one of the tips that he gave us in the class.
Here are the materials that you use.
I use a salt and pepper shaker to store the working Pumice and Rottenstone. Just don’t put them on the picnic table or get them to your kitchen. It could mess up a bunch of food. I believe that they make a FFFF version of Pumice. The number of F’s equate to the fineness of the grit in the polishing compound. It doesn’t make any difference which one you use. I use Butchers paper as a work surface because it has a plastic surface on the paper.
The tools are:
I use the metal putty knife to mix the Boiled Linseed Oil (BLO) and the Pumice or Rottenstone. I mix it on the board that I’m going to use it on. I use a rubber spreader that I bought at a Professional Automotive Finish store. It’s used to spread body putty in damage of cars. I’ve also used a small window squeegee and I’ve used the putty knife. I stuck a small piece of Formica because it could also possibility be used.
I used BLO for this demo but I might also try Danish Oil because it dried harder than just BLO. A homemade version of Danish Oil is 1/3 or each Mineral Spirits, BLO (Deft says that they use Teak Oil) and Varnish.
Dump some oil on the board and then dump some rottenstone on top of it.
Mix it up and make it thick. Remember though that the oil soaks into the wood so it will continue to get thicker as you use it.
Spread it over the board and force it into the pores of the wood. I’m now using the rubber spreader.
Note I’m using a sample of Red Oak and Walnut. When you drag the slurry you want to pull it across the grain. You don’t want to go with the grain because you might pull the slurry out of the pores.
It will slip over the edges, but if you are doing a piece of furniture, you might only want to do this on the top because that’s where the pores would be most visible.
You will also note that the rottenstone also darkened up the sapwood of the walnut piece. Use masking tape and paper to keep it from where you don’t want it.
The next sample will be using Pumice.
Pour your oil.
Then mix in the pumice.
Force it into the pores. NOTE: I’m not using the rubber block on the pumice because the abrading effect of the pumice could actually cut some of the black rubber into the slurry. I didn’t want that.
Do the final pass to force the slurry into the pores and clear off all extra.
All done with the pumice demo pieces.
Now the control pieces. Just the BLO and no filler materials.
Now finished these pieces.
These are the three sets of the boards. I’ll let them sit for a couple of days so that the finish will harden some. It’s this time where the Danish Oil would be faster. The Rottenstone is on the left. The Pumice is in the middle and the control piece with only BLO is on the right. These boards are after 12 sitting but still not wiped off.
I’ll continue this in another blog in a couple of days.
-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware firstname.lastname@example.org †