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Question about French polishing
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Author:  Ken Mitchell [ Fri Jan 07, 2011 11:51 am ]
Post subject:  Question about French polishing
The thread on 'Goals for 2011' made me start thinking about several things, one of which is to learn how to do French Polish (whoa... isn't that's the same spelling as for a person from Poland!?). Which prompted me to think about a project that I just completed - a large hardwood chessboard - which I ended up finishing basically with what I would call 'polished shellac'. I turned out very nice, and now I'm wondering if I could do this process instead of, or as a base for, true French Polish.

Basically, after pore filling the wood - which was a combo of wenge and maple - I put on several coats of shellac as a seal coat, just wiping it on with a small fold of cotton cloth. While leveling a few coats at one point, and just on a whim, I decided to go through the varioius grits of sandpaper, then micro mesh, and it came out looking quite nice. It got a little thin in a few spots, so I redid the process, with about 12 coats of shellac (Zinser), and ended up with a wonderful shine.

So my question is... Are there any advantages / disadvantages to doing a finish this way (vs. true FP)? Could you lay down a base coat for further, true FP by doing it this way? I DO want to learn to do authentic FP at some point; this might be just for the time being...

I'll try to post a pic of the board in a few days (it's at my office right now).

Thanks for any suggestions and/or input.
Author:  Mark Groza [ Fri Jan 07, 2011 12:18 pm ]
Post subject:  Re: Question about French polishing
You can finish that way, but it won't be as durable of a finish as regular FP.
Author:  DennisK [ Fri Jan 07, 2011 2:41 pm ]
Post subject:  Re: Question about French polishing
Have you tried spilling water on that chess board yet? laughing6-hehe
Bet it will get ugly white spots if you do. That's the big difference. Wiped on, you get tiny pores in the finish that weaken it. French Poland you get a single solid layer that's hard and waterproof... but still ridiculously thin so the hard part doesn't help a whole lot.

I'd have to see your surface in person to properly judge, but I love the look of a glazed FP surface (running the pad over it with mostly just alcohol, which I believe dissolves the very surface and lets it smooth itself out by surface tension) rather than sanded and buffed finish. Or is that what you did, came up shiny on its own after the 12 coats of shellac after sanding?
Author:  Ken Mitchell [ Fri Jan 07, 2011 3:15 pm ]
Post subject:  Re: Question about French polishing
Dennis,

No, it took going through the whole series of grits, then the same with micro mesh. It was quite a bit of work.

I'm just curious about FP as a finish now. I keep my guitars inside, use a small towel over the lower bout when playing, wipe them after use, etc., so I might be able to use FP for my OWN guitars. But from what I've read, it seems that guitars with FP are somewhat vulnerable to moisture (body oil and sweat mostly, I would assume).
Author:  DennisK [ Fri Jan 07, 2011 3:40 pm ]
Post subject:  Re: Question about French polishing
I think some people's sweat can cause problems with FP. Not sure what the exact effect is though, or how common it is. My own sweat doesn't seem to have any effect on shellac, but it does on tool steel. Fingers turn darker and darker black as I work. Very annoying, because the blackness rubs off on wood, so I have to be extra careful with spruce. I've heard that happens for some steel string players as well, but apparently the alloys used for strings don't react with my sweat like tool steel does. Or I don't play hard enough :)

I'm convinced that any claims of water damaging French polish are due to improper technique, rather than the finish itself. Mine seems to be entirely waterproof, except for some tiny corners where I had masking tape for the bridge so the pad couldn't get full pressure. Got some whiteness there from water while gluing the bridge, but scratched off to good shellac and it's not very visible anyway. I do wonder how many instances of sweat damage were also due to application rather than chemistry.
Author:  Michael.N. [ Fri Jan 07, 2011 4:36 pm ]
Post subject:  Re: Question about French polishing
From a few tests that I've done with Shellac it seems fairly resistant to water. That does not mean to say that it is resistant to certain players sweat though. Then again that may depend on the type of Shellac that is used and if any drying oil is incorporated into the finish.
Padding the stuff on in straight lines isn't that much different to the full blown method, although it may be more difficult to keep the film even. I suspect that it's the degree of pressure and how many times you actually 'polish' the surface that is the real difference. A simple wipe on isn't that much different to brushing the stuff on - almost equivalent to spirit varnishing with a brush.
Author:  Andy Gamble [ Mon Jan 10, 2011 1:44 pm ]
Post subject:  Re: Question about French polishing
Shellac will dissolve in alkaline water, and it seems that some people have slightly alkaline sweat. Dennis, what you describe with the tool steel indicates that your sweat is probably acidic.
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