French Polish question

[Harold Hensley]

In the description of how to French Polish on the Frets.com website, is the finish on the old mandolin also French Polish or was it something else. I'd like to know if one can do a French Polish over an older satin finish (2004 Seagull) without having to sand down to the wood.

Thanks Harold Hensley

[Greg Mirken]

Shellac, the basis of French polish, will stick to just about anything, and just about anything sticks to it as well. What's your goal? If you just want to shine it up a bit there are easier ways.

[Harold Hensley]

I think I might want to put a good french polish on the top if I don't have to sand all the way down to the wood. Any suggestions about how to prep the top for this?

[Ned Knepp]

Harold,

 Shellac isn't the most durable of finishes and the process of French Polish isn't like just brushing on a finish and waiting for it to dry. It takes a bit of practice to get it right. To learn the technique, I'd suggest that you get a plank of wood or start with a smaller instrument/project.

My first project was a mandolin. It was relative easy because the neck had been removed as well as the pick guard, bridge and tailpiece. In other words it was a small body with nothing on it to get into the way. The body was small enough that I was able to work all of one surface fairly easily. Even at that, I still messed it up the first time and had to strip it and start again.  

I strongly recommend that you get a fairly decent size board and practice on it before touching your guitar. There's a lot of little things you will probably want to learn on a piece that doesn't really matter before you start applying the process to your guitar. You will want to keep the shellac finish thin since you are not going to remove the original finish, so getting a feel for how it builds will help you a lot in that area. The finish build is very thin each pass but you're going to need to build enough shellac to give it some durability. You might also want to practice starting where you left off. Layer's of shellac melt together very well so it's relative easy to build some finish, stop and return later to build more. I find that there's a bit of a "startup" process that needs to happen when I do this. The first couple of passes may feel odd as you restart the process and I've found that I need a bit of patience to get things flowing again.  I think it may have something to do with the pad and the distribution of finish in it as I start the process but I also think it takes a bit to get the new layers and the older layers to start blending. Once I have it started again, it becomes easier to keep the build going. You can feel when the pad needs some more finish in it or when the finish may need a touch of oil. It just takes some practice. 

If you haven't already done so, read up on  the process as much as you can. One of the things I figured out is that experiences vary but there's some good information available that can help you avoid a lot of mistakes.

I'm not trying to talk you out of it but I've run into some people that try it with out some prep and with doing much research or practice and decided it's not for them when it doesn't work out. 

Now that I've said all of that, Greg makes a good point that there are other ways to shine up your finish some.  

[Harold Hensley]

Thanks much for your response. I have done a little French polishing but am certainly not good enough at it that I won't try it again without practice first. I have read several articles on the technique and most are quite clear. I mainly want to know if I need to do ANY sanding before I begin the actual French polishing. Thanks again for your help.

Harold

[Ned Knepp]

As Greg pointed out, shellac stick to almost anything. It may be possible that a very detailed cleaning  and dewaxing will do the trick but, if it were mine and I was absolutely sure that I might not want to reverse it, I would probably do a light 220 sanding on the surface and tack it off before starting.  

BTW, I'm not sure but I seem to remember that Seagull's are finished with lacquer. Whatever it's finished with, I would do some testing to determine if alcohol has any effect on the existing finish. If that's the case I would go easy for the first bit until I could be sure that I was building only shellac without pulling an older, non-shellac, finish in the process. Personally, I tend to thin my shellac more that most so it may not be an issue for others but it's always better to know if the solvent will affect the existing finish ahead of time 

[Harold Hensley]

Thanks again.

[Hesh Breakstone]

Be ready too for the ensuing carpel bicep that invariably happens to me when I French Polish...

[Ned Knepp]

You made me laugh, Hesh. It IS a workout.