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Advice Needed - French Polishing
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Author:  bcombs510 [ Thu Jun 02, 2016 12:46 pm ]
Post subject:  Advice Needed - French Polishing
Hello,

I'm working on my second build and I'm at the finishing stage. For the first guitar I completed I used Enduro-Var sprayed on with an HVLP sprayer. That finish worked out really well and after buffing was very smooth and clean looking.

For this guitar I decided to try French Polish. I've got the body and neck pore filled with z-poxy. To my eye everything looks level in close up inspection. But.... :)

After just hitting the back a couple of passes with the shellac I can see all kinds of scratches and dents in the pore fill.

My question - If I just keep going with the French Polish will I be able to build it up and level it out and therefore these minor blemishes won't matter? The reason for the question is I'm guessing that the Enduro-Var built up quickly and I just didn't notice this. Will the FP do the same?

It's hard to take pics of it but I could try that if needed. I'm thinking I should just charge ahead but would appreciate any feedback.

Thanks!
Brad
Author:  Hesh [ Thu Jun 02, 2016 1:14 pm ]
Post subject:  Re: Advice Needed - French Polishing
Hey Brad: Shellac when FPed builds VERY slowly so you will be doing it for days.... Complicating things is that shellac sticks fine to epoxy but epoxy has issues sticking to shellac. This means removing the shellac and continuing with the epoxy until it's completely filled before starting the FPed shellac.
Author:  bcombs510 [ Thu Jun 02, 2016 1:53 pm ]
Post subject:  Re: Advice Needed - French Polishing
Thanks, Hesh. I'll keep going and see how it builds. I'm following the video that Robert O'Brien put together which is supposed to speed up the process some. I don't have anything to compare to so I can't say for sure if it is faster than the traditional method.
Author:  dpetrzelka [ Thu Jun 02, 2016 2:47 pm ]
Post subject:  Re: Advice Needed - French Polishing
Brad,

From my limited experience doing FP with Robbie OBrien's method is that it still builds very very slowly - faster than the most traditional method - but with FP there is no great depth of build I'd ever hope to achieve.

What I believe Hesh is recommending, and what I would recommend, is turn back now - get that initial pore fill flat and smooth so you have a great base to build upon. Your arm will thank you.

PS - I found Robbie O'Brien's French Polish video very helpful, a very smart investment.
Author:  DennisK [ Thu Jun 02, 2016 3:26 pm ]
Post subject:  Re: Advice Needed - French Polishing
French polish is not like lacquer. There basically is no build-up of finish. As soon as you get the surface flat, it only takes a few minutes to stretch a microscopic sheet of shellac over it to make it shiny, and you're done. All the work is in filling the texture of the wood.

IME, shellac never fills sanding scratches. I always end up going back to the scraper. But I'm not entirely sure why, because the pad should force the shellac into the low points and level off the high points. It works on scraped softwoods to fill the micro-texture of the wood and just leave the large scale corduroy texture, but for some reason sanding scratches always continue to show up in certain lighting...
Author:  Hesh [ Thu Jun 02, 2016 4:28 pm ]
Post subject:  Re: Advice Needed - French Polishing
dpetrzelka wrote:
Brad,

From my limited experience doing FP with Robbie OBrien's method is that it still builds very very slowly - faster than the most traditional method - but with FP there is no great depth of build I'd ever hope to achieve.

What I believe Hesh is recommending, and what I would recommend, is turn back now - get that initial pore fill flat and smooth so you have a great base to build upon. Your arm will thank you.

PS - I found Robbie O'Brien's French Polish video very helpful, a very smart investment.


Exactly! [:Y:] Thanks Daniel!

Film thickness with FPed shellac is so very much thinner than say lacquer or today's finishes such as cat poly that with FPed shellac surface prep has to be dang near perfect before starting to wear out your arm....

That's why I'm suggesting prepping the surface completely with epoxy because it builds way better before deploying the shellac.
Author:  doncaparker [ Thu Jun 02, 2016 5:13 pm ]
Post subject:  Re: Advice Needed - French Polishing
DennisK wrote:
As soon as you get the surface flat, it only takes a few minutes to stretch a microscopic sheet of shellac over it to make it shiny, and you're done. All the work is in filling the texture of the wood.


Amen. Truer words were never spoken. The hard work in a French polish is all about the surface prep and pore filling. Once those tasks are done well, the gliding on of actual coats of finish is easy as pie. The other side of this coin is that, if the surface still has problems (even teeny tiny problems) or pores unfilled, there ain't no amount of shellac that is ever going to cover up those problems. Or, at least it will feel that way if you try. You will drive yourself batty trying to use shellac to fill a pore that made it past the prep stage.

This is where traditional methods of filling pores in a French polish have an edge. If you use the pumice method, for instance, and if you you mess up and leave some problem areas, and then try to put on finish coats of shellac, you can always go back and fill pores again when you discover the problem areas.
Author:  bcombs510 [ Thu Jun 02, 2016 6:04 pm ]
Post subject:  Re: Advice Needed - French Polishing
Thanks, all. I may sand off the little bit of shellac and go back to the safe enduro-var. Thanks for the feedback!


Sent from my iPhone using Tapatalk
Author:  WaddyThomson [ Thu Jun 02, 2016 9:47 pm ]
Post subject:  Re: Advice Needed - French Polishing
You can always do some pumice filling to finish the job. Never too late to add some pumice filling. I have done it many times, even over Zpoxy fill.
Author:  Alain Desforges [ Fri Jun 03, 2016 4:23 am ]
Post subject:  Re: Advice Needed - French Polishing
Waddy beat me to it. Never too late for pumice, and in my opinion, nothing beats the look of it. Also, it's super fast. If you don't want to sand off the shellac you have on there already, just use it work up a slurry with the pumice.
Author:  doncaparker [ Fri Jun 03, 2016 6:17 am ]
Post subject:  Re: Advice Needed - French Polishing
I think it is probably important to mention something about filling using the pumice method. Notice I didn't say "filling with pumice." That's because the stuff that fills the pores should be mostly tiny wood dust, shellac, and only the amount of pumice needed to abrade the wood and shellac so it will come loose and fill the pores. Pumice acts more as an abrasive than as a filler. The filler should be wood dust and shellac. If you try to fill with pumice, the stuff filling the pores is a little bit of wood dust, shellac, and a lot of pumice. This shows up as white specks under the finish, and that's a bad thing.

I only know this because of the old saying: Good judgment comes from experience, and experience comes from bad judgment. I've made the mistake of using too much pumice.
Author:  mflazar [ Fri Jun 03, 2016 8:28 am ]
Post subject:  Re: Advice Needed - French Polishing
After French polishing over 100 new guitars and re polishing a few dozen more, I beg to disagree with some of what is said here.

1. Shellac can and will build a body and it will fill pores and sanding scratches. Certainly it is much better to have the pores well filled and start with a perfect, well filled surface but you can fill with shellac alone.

2. French polishing works better if you have a routine. I measure the amount of shellac I put onto my pad. I charge the pad only once and polish until it is dry, then leave the surface to dry for at least an hour. Letting each coat dry between applications is part of the secret to a quick body
build.

2. Pumice, when lightly rubbed onto an alcohol wet pad so that it is "cleared" (from white to transparent) and then padded onto the surface will combine with the shellac. The combined shellac/pumice mixture can do an excellent job of filling as it redistributes into the pores.. Waddy is right when he says it's never too late to Pumice. Properly "cleared" pumice will not show up as white flecks in the pores.

I think the most important thing about French Polishing is that any polishing you do can add value no matter how messy it looks so you should never have to "start over". A little sanding will straighten it out and you're good for the next coat. Any work you do adds to your experience and as you gain experience you will continuously get better at it.
Author:  WaddyThomson [ Fri Jun 03, 2016 11:16 am ]
Post subject:  Re: Advice Needed - French Polishing
Amen!
Author:  doncaparker [ Fri Jun 03, 2016 12:43 pm ]
Post subject:  Re: Advice Needed - French Polishing
mflazar wrote:
Properly "cleared" pumice will not show up as white flecks in the pores.


Well, that's the trick, isn't it? The cause of improper clearing is using too much pumice. Someone riding the line between "just enough" and "too much" pumice can easily go too far and experience the problem I mentioned.

I obviously bow to your superior experience, Michael, but as I said, my experience is riddled with messing this up, so I'm gun-shy about using too much pumice. I feel that it's a common enough problem for non-professionals (like me) that it deserves a mention and warning.

Clearing the pumice is an interesting thing. If the pumice touches alcohol, it gets harder to see. That's good. But eventually, the alcohol is going to evaporate. If the pumice and alcohol never combine with shellac, or not enough shellac, then what is left behind after the alcohol goes away is just (or mostly) pumice, with either no shellac or not enough shellac to keep it hard to see. That pumice goes back to being white, and we have the problem that I'm describing. Whether the other ingredients of the "left behind" filler are wood dust, shellac and pumice or just shellac and pumice, using too much pumice shows up.

I'm just trying to warn other non-exceptional students like me of a common problem with French polish.
Author:  DennisK [ Fri Jun 03, 2016 1:03 pm ]
Post subject:  Re: Advice Needed - French Polishing
Alain Desforges wrote:
Waddy beat me to it. Never too late for pumice, and in my opinion, nothing beats the look of it. Also, it's super fast. If you don't want to sand off the shellac you have on there already, just use it work up a slurry with the pumice.

What kind of pumice are you using? I have the stuff from LMI, and despite my many attempts, it still takes hours and hours (and a lot of alcohol) to get a guitar mostly filled. I'm starting to suspect that my pumice is too fine...
Author:  WaddyThomson [ Fri Jun 03, 2016 1:18 pm ]
Post subject:  Re: Advice Needed - French Polishing
LMI sells 6/0 pumice. It's what I use mostly. I have some 4/0, but find it harder to work with. It's pretty coarse, comparatively, and doesn't clear as well. It's particularly not good when the process is well on it's way to being a finish. In the early stages with just spit coats and the beginnings of pore filling, the coarse is fine, as you get a lot of wood in the mix then.
Author:  mflazar [ Sun Jun 05, 2016 9:27 am ]
Post subject:  Re: Advice Needed - French Polishing
doncaparker wrote:
If the pumice and alcohol never combine with shellac, or not enough shellac, then what is left behind after the alcohol goes away is just (or mostly) pumice, with either no shellac or not enough shellac to keep it hard to see. That pumice goes back to being white, and we have the problem that I'm describing. Whether the other ingredients of the "left behind" filler are wood dust, shellac and pumice or just shellac and pumice, using too much pumice shows up.
I'm just trying to warn other non-exceptional students like me of a common problem with French polish.


Certainly the warning makes sense as long as we're suggesting that too much pumice should be avoided as opposed to saying it should not be used at all.

But if you do get some "white" pores, try putting a drop of finishing oil (tung oil works well) onto them, Let the oil dry for 10 minutes or so and lightly wipe it off. The oil should "clear" the pumice and it should remain clear when the oil dries. You can also use oil to clear the little white lines you might get in corners (where neck meets body and fret board meets top) just brush it into the corners with a fine brush, let it dry and wipe it off with a soft cloth.
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