What is a French Polish technique on a lathe?

[Brian Kent]

I already had a number of dewaxed shellac layers. Yesterday I spent a lot of time applying more dewaxed shellac with denatured alcohol and a bit of mineral oil mixed together. The lathe was on the minimum speed of 250 rpm.
This morning I used the alcohol to take off the oil and move the shellac. The lathe was off and I moved in long circles mainly bottom to top to smooth out the rings.

I can see that it is not done. Still dull at the base. A dull area near the rim, and a little bit left of the circles.
I can repeat the process, either using mineral oil or blo in the mix.
Will I do this many times? Will it be glossy when I am done or will I need to Beall-buff after it hardens?

Thank you all for your help.

[Mark Greenbaum]

The french polish technique I subscribe to was from a guitar building forum, and the demonstrator used super blonde flake shellac dissolved in DNA or PGA, and applied liberal coats with dauber made of lint-free cotton with cotton balls inside. The coats melt in the previous layer, and the final coats are lubricated with drops of olive oil. I have hand applied and applied while on the lathe at low speeds, and gotten a nice luster that is natural, and water-repellant, as well as easy to maintain.spalted-maple-bowl-1.jpg The mentors at the club said it's not a durable finish for a salad bowl, but we wash it in dish soap and wipe off fine. I have not had to repair it yet, and that's 4 years now.

Here's that video link: http://www.finewoodworking.com/how-to/video/how-to-create-a-sunburst-finish.aspx

[Allan Speers]

The french polish technique I subscribe to was from a guitar building forum, and the demonstrator used super blonde flake shellac dissolved in DNA or PGA, and applied liberal coats with dauber made of lint-free cotton with cotton balls inside. The coats melt in the previous layer, and the final coats are lubricated with drops of olive oil. ....

Mark, are you sure he didn't have pumice inside that dauber? (often referred to as a "tampon" BTW) I used to build classical guitars, and that was the standard way to french polish. It would be a royal PITA without it.

[Mark Greenbaum]

Mark, are you sure he didn't have pumice inside that dauber? (often referred to as a "tampon" BTW) I used to build classical guitars, and that was the standard way to french polish. It would be a royal PITA without it.

Nope, no pumice. I don't own any pumice (except a 5 lb chunk I picked in Oregon). I did sand while still on the lathe, and burnished it with shavings. The first coat was a flood coat, and let it sink in and seal the wood. This bowl is spalted silver maple. Then 0000 steel wooled. Also steel wooled after every 3rd additional coat (I applied about 12 coats), then good old fashioned elbow grease and final coats with olive oil lube. After it settled in, I did put a coat of Johnson's paste wax (because I love the smell of that stuff - reminds me of when I was a kid, and Mom would wipe off the furniture with it). Then I lightly rinsed it with warm water and a towel to dry it off.

[Jon Nuckles]

Brian --
Because the alcohol will dissolve the shellac as you are spiriting off the oil, it is very important to keep the rubber moving and control the pressure or you can easily spoil the finish you have achieved. I have also found that using too much oil when applying the shellac can make the finish soft and impossible to rub out to a high gloss. I would try to do the last step with the lathe on. If the finish is soft, however, my only success in getting a good finish is by removing the finish (with liberal doses of alcohol) and starting fresh.

Allan --
I have used pumice to fill the pores, but not beyond that point in the process. Do you use pumice throughout the process?

[Allan Speers]

Thanks, Mark.


I think the fact that you didn't use pumice is why it took 12 coats. When I built guitars, the spruce tops used to take maybe three short sessions, because the pumice creates a swarth that fills-in the pores. You don't see it when finished, so for me this is a no-brainer, but obviously there are other workable methods. I did a few maple bodies, and they didn't require pumice, as the pores fill much faster than spruce & rosewood.

[Allan Speers]

Allan --
I have used pumice to fill the pores, but not beyond that point in the process. Do you use pumice throughout the process?

Not the last coat. - but again, this is a guitar-finishing thing. (Extremely standard with luthiers.) I don't profess to know what's best for all furniture & all species of wood. In fact, I'm finding this thread fascinating.

[Doug Herzberg]

Not the last coat. - but again, this is a guitar-finishing thing. (Extremely standard with luthiers.) I don't profess to know what's best for all furniture & all species of wood. In fact, I'm finding this thread fascinating.

I'm learning a lot, too, Allan.

Brian, I don't use this method often. When I did, I was usually turning green to finish and wanted something that would be done when I took it off the lathe. I fiddled with the finish until I was satisfied, often taking everything off with DNA and starting over, but when I was done, I was done. The whole point for me was to have a finish I didn't have to keep coming back to. I was able to get some satisfactory results, but it takes a little practice.

[Mark Greenbaum]

Allan:

I did not use pumice because I don't think that video was geared towards the filling of the wood pores, as much as learning to do the dyeing and bursts then covering with a French Polish. The silver maple was sealed after the first coat. And I had a good lustrous shine at about 4 coats; I just wanted more for the durability. Recently a demonstrator at our club show how to seal with 50/50 Helms Sparathane and mineral spirits with lathe spinning about 50 rpm. He sanded lightly with about 280 grit, and wiped, and applied more coats of full strength Helms Sparathane, a coat every 20 minutes. Great finishes with minimum work.

Thanks, Mark.


I think the fact that you didn't use pumice is why it took 12 coats. When I built guitars, the spruce tops used to take maybe three short sessions, because the pumice creates a swarth that fills-in the pores. You don't see it when finished, so for me this is a no-brainer, but obviously there are other workable methods. I did a few maple bodies, and they didn't require pumice, as the pores fill much faster than spruce & rosewood.