Some things that I've learned about finishing. Some of them I also use. #2: Home made wood fillers, Pumice and Rottenstone.

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Blog entry by Karson posted 06-24-2007 01:10 AM 34696 reads 15 times favorited 15 comments Add to Favorites Watch
« Part 1: Using Scrapers Part 2 of Some things that I've learned about finishing. Some of them I also use. series Part 3: Wood filling and finishing »

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. Appomattox Virginia [email protected]

15 comments so far

View Roger Strautman's profile

Roger Strautman

657 posts in 4582 days

#1 posted 06-24-2007 01:43 AM

Thanks Karson! I learned something new today. Now can I go to the house for supper? LOL!

-- " All Things At First Appear Difficult"

View Karson's profile


35194 posts in 4849 days

#2 posted 06-24-2007 01:55 AM

Rog: Glad to contribute to your base of knowledge. And, also allow you to go eat.

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

View MsDebbieP's profile


18619 posts in 4609 days

#3 posted 06-24-2007 02:47 AM

isn’t that interesting!!!
“across the grain”.. makes sense!

-- ~ Debbie, Canada (, Young Living Wellness )

View FMOmbr's profile


47 posts in 4533 days

#4 posted 06-24-2007 05:02 AM

My wife wants to know when you took Jeff Jewitt’s class; she took a class with Jeff on finishing @ Marc Adams School and uses this technique on mahogany with much success. You have been generous with your knowledge. Thanks.

View Karson's profile


35194 posts in 4849 days

#5 posted 06-24-2007 06:08 AM

I took this class

Hand Applied Finishes
By Jeff Jewitt 6/22/2002

At Thaddeus Stevens College of Technology

The host of the class was Steve Latta who was the administrator of the woodworking program at the university. Steve is quite well known for his Federal Period woodworking, and writes a lot of articles in woodworking magazines.

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

View Sawdust2's profile


1466 posts in 4536 days

#6 posted 06-24-2007 11:57 AM

Thanks, Karson.

I’ve been using pumice and rottenstone for years and never saw this as an option.

You can teach an old dog new tricks!

-- No piece is cut too short. It was meant for a smaller project.

View oscorner's profile


4563 posts in 4759 days

#7 posted 06-24-2007 01:43 PM

I prefer the pumice application because it doesn’t affect the original look of the wood grain. Of course, I am sure there are times that the rottenstone effect of the grain would be desireable. Karson, you are doing a wonderful job of sharing this information. I never knew about using either of these for a wood filler. I usually use wood glue and sawdust to patch and avoid wood fillers because of the fact that it is almost impossible to match the wood to the filler.

-- Jesus is Lord!

View TheGravedigger's profile


963 posts in 4472 days

#8 posted 06-24-2007 05:01 PM

Sweet technique! I especially like the way rottenstone brings out the grain in oak. This would be really interesting after fuming white oak in the Mission style. Hmm…something to play with.

-- Robert - Visit my woodworking blog:

View furnitologist's profile


198 posts in 4461 days

#9 posted 06-24-2007 05:28 PM

Hey Karson….....SWEET…......Danish Oil and the Pumice…...super tip…...never knew that…....THANKS!!!!


View cheller's profile


254 posts in 4557 days

#10 posted 06-24-2007 08:55 PM

I just tried a similar method, from an article in FWW (I think I’ll have to look). The method in the article had you sprinkle the pumice on the wood then rub in with a rag soaked in boiled linseed oil. While working on it I decided it would be much easier to mix the two first and apply with a putty knife – which is of course exactly what you showed here. I do like the look of the piece so far. I’ve got a second piece (foot stool) to do and I think I’ll try your method. Results will be posted later.

Incidentally the article also suggested plaster of paris as an alternative wood filler which would, of course, lighten the grain. It was suggested mostly as a quicker alternative.

-- Chelle

View Karson's profile


35194 posts in 4849 days

#11 posted 06-24-2007 10:06 PM

Cheller: I’ve done something similar to what you suggested but it was done while veneering. In that case you used Shellac and sprinkled the pumice on the French Polishing pad and you rubbed the surface. It then placed a combination of wood dust and pumice into the pores of the veneer along with the shellac. It is used as a surface filler as you do the French Polish.

The boards that I pictured above were placed outside today in the sun. The oak board with just the BLO started to weep a little oil to the surface as the board heated up. The Pumice Oak board had a couple of spots and the Rottenstone version had none. That might also be a case where the Pumice and Rottenstone soaked up any excess BLO. Or, it’s a case where the slurry was thick and not as much BLO soaked into the surface anyway.

The walnut boards had no oozing at all on any of the boards.

The pores on the two boards that had the filler are completely full while the BLO versions still have open pores.

I was (and may still today) make my own Danish Oil and try the pumice and rottonstone again on the oak. I got lots of pieces like the ones shown. They were from the toy club and I was going to make 800 wheels with the boards. I can still use them for that because I only put the hole saw part of the way through and then use a resaw to free them up.

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

View cheller's profile


254 posts in 4557 days

#12 posted 06-25-2007 06:38 PM

I took a look last night and the article I mentioned was by Jeff Jewitt from FWW May/June 2005.

-- Chelle

View Karson's profile


35194 posts in 4849 days

#13 posted 06-25-2007 08:28 PM

Yes same instructor, for the class I took. Jeff also has some books on finishing. Here is his website

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

View Zuki's profile


1404 posts in 4525 days

#14 posted 07-03-2007 02:23 AM

Interesting. I just finished watching the Wood Whisperer who did some grain filling as well. He showed two approached . . . one using oil and the other using a commercial grain filler.

-- BLOG -

View .'s profile


21 posts in 1954 days

#15 posted 07-14-2014 03:00 AM

Hi Karson.

Were there ever any updates on this experiment? I am refinishing a late 19th century oak table and I would like to grain fill using period techniques. How did the BLO and pumice end up?

-- "As a dog returneth to his vomit, so a fool returneth to his folly." And so I shall leave this godless forum and not return again.

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