Some things that I've learned about finishing. Some of them I also use. #3: Wood filling and finishing

The continuation of the Pumice and rottenstone as wood fillers.

I let the BLO (Boiled Linseed Oil) harden for 1 week on the boards.
This is my spraying table that I use. The bottom is on a lazy susan swivel so that it can turn 360 Degrees. I made a block that I can set on top of it that has a bunch of screws through the plywood so that I can put items on top of the screw points and not have the wood sitting on the flat surface and get finish creep under the boards.

The spray gun that used for this demo is shown. It’s a gravity flow sprayers and it is not HVLP. I probably had the pressure at 100 lbs. Because I forgot to set it lower.

The walnut boards that had BLO and rottenstone (Left), Pumice (Center) and just BLO on the right were sprayed with Zinsser sanding sealer shellac. 2 lb cut – thinned about 25% so it was probably a 1.5lb cut.

The pores on the rottenstone were very good. Almost all of the pores were filled with the rottenstone. I used a walnut board with a lot of white wood to show the effects of the rottenstone on the color of the pores.
You can see that the pumice board is quite smooth and all of the pores seemed to be filled. The board on the right was just the BLO and the pores are quite visible. In the picture. The darker walnut looks a little better to me with the rottenstone than the pumice, but, if sapwood is visible I’d go with pumice.

This is a set of Oak boards with Rottenstone and BLO (Left) Pumice (Center) and just BLO (Right). These boards were also sprayed with the Zinsser sanding sealer.
No sanding was done on these boards after the application of the Rottenstone and Pumice. I did use a scraper to lightly remove all excess surface materials. I did that after about 24 hours before the BLO setup hard.

The pore filler of the rottenstone is quite visible and quite dramatic. With stain it might be a great combination. The pumice board is a little darker than the straight BLO board. The pores are not depressed on the filled boards like it is on the straight BLO board. It could almost be possible to do a second coat of the filler, but, it’s not really necessary. If you sprayed it and then sanded it flat, it would be possible to have a totally smooth oak board. The pumice didn’t darken the oak board enough to make it appear strange.

I made another test that I didn’t report in an earlier blog in this series. I stated that I might try Danish oil instead of BLO because it would dry faster. So I made my own Danish Oil. !/3 BLO, 1/3 Varnish – I used some flooring Poly that I had left over from a flooring refinish job I did a couple of years ago. And 1/3 Mineral Spirits. I mixed about 1 oz of each into a plastic squeeze bottle.

Again the rottenstone and Danish Oil (Left) Pumice (Center) and just Danish Oil (right). Some of the slurry that was visible on the ends of the boards was a little harder on the Danish Oil versions of the boards than the BLO versions. The Danish Oil Versions of the boards were sprayed with Deft thinned about 50%.
The rottenstone board looks like the BLO version, the pumice board is a little darker almost as if the board got contaminated in some way. I mentioned in an earlier blog that I didn’t use a rubber spreader on the BLO version of the boards. I might have used it on the Danish Oil versions, so what you might have here is some rubber that was ground off while spreading the pumice/oil slurry and forcing it into the pores. I made a point of using a putty knife to spread on the BLO versions, but I might have failed to do it on the Danish Oil Version. Or the board was a little darker. The difference between the Danish Oil/Pumice boards is a lot darker than the just Danish Oil board. So I would attribute it to Operator and not the finish.

This is a little closer close-up of the Pumice/BLO and BLO only on Walnut. The pores are quite visible on the board without the filler.

A close up of the BLO/Rottenstone Oak board.

The BLO/Pumice Oak board.

The Danish Oil/Rottenstone Oak Board.

The Danish Oil/Pumice Oak Board.

This is a board that I finished in a French polish class that I took.

I used the BLO and Rottenstone Slurry on this board, but because of time constraints in the classroom it was only on the board for about 1 hr, so the full effect of the BLO hardening did not happen. The pores were finally filled with French Polish. Put down a coat and then use 600 grit with mineral oil and sand it. It finally filled all of the pores with shellac. It was over 30 days before I got all of the pores filled. Now what I’d do is fill it with Danish Oil and Rottenstone, let it dry for a day. Scrape off the surface and if additional filling was required I’d do it again. Then lightly sand to get the surface clear of rottenstone slurry. Spray about 4 coats of shellac. Use a scraper to smooth the surface and then sand with 400 grit and then 600 grit with Mineral oil and then start the French polishing. Fill all of the left over pores with shellac and then level the surface with sanding and get on with the finishing.

Post any questions you might have.
Someone asked how I spray shellac. It’s just like any other finish that I might spray.

Let me give this note, in case you might not have read my blogs on French Polishing.

NOTE: If you are going to sand shellac or possibly any finish with mineral oil and sandpaper. It is a requirement to put an oil finish on first. BLO – Danish Oil – Tung Oil something. The reason being that you will have voids in the finish when you do some of the early coats of smoothing and what happens is the sanding oil seeps through those voids and you end up with splotches in the wood, because some of it will have an oil and others will not. It’s best to make it all have oil prior to putting on the top coat.

Again I say if you sand with oil , have oil on the wood before the first finish coat. If you don’t sand with oil, this doesn’t apply to you.

-- Karson Southern Delaware karson_morrison@bigfoot.com