French Polish

[olddog]

Hi. I just started french polishing a few months ago. I have a few questions about grain filling and glazing. I'm currently doing a mohogany sg body, and some areas just seem to resist grain filling, no matter how much I keep sanding back the body coats and then grain filling again. The glazing question I have is that I can't seem to get the staight lines out of the final result. Before I glaze, the finish seems almost perfect, the glazing is like a step backward. I end up having to use polishing compouns to get back to the shine I had. Any ideas?

[fryovanni]

Not sure how you are going about grain fill. Are you using pumice or epoxy or??? Sounds like you may be trying to do too much filling with the shellac itself(which shrinks back quite a bit). As far as the glazing. Maybe you are loading a little too much alcohol, or going a little slow with the Munica. Please let us know how you are doing your fill.

Peace,Rich

[olddog]

Not sure how you are going about grain fill. Are you using pumice or epoxy or??? Sounds like you may be trying to do too much filling with the shellac itself(which shrinks back quite a bit). As far as the glazing. Maybe you are loading a little too much alcohol, or going a little slow with the Munica. Please let us know how you are doing your fill.

Peace,Rich

Hi. My initial grain filling was with pumace, and that was applied over two wiped on coats of shellac. After that I started bodying, using just shellac, for 5 or 6 sessions, With a day between sessions. I wet sanded between each body session. Then, I sanded most of that off and grain filled again. Most of the guitar is filled, there are just a few areas and a random pore showing through. The glazing I'm going in a straight line along the grain, using 5 or 6 drops of alcohol and 1 drop of shellac for each pass across the guitar. I'm getting the "haze" behind the munica, but I'm taking away the gloss that was there after the last bodying. I guess I would be happy with abrasive buffing, but I read that glazing produces a deeper gloss. I'll keep trying if it does. Thanks

[fryovanni]

Not sure how you are going about grain fill. Are you using pumice or epoxy or??? Sounds like you may be trying to do too much filling with the shellac itself(which shrinks back quite a bit). As far as the glazing. Maybe you are loading a little too much alcohol, or going a little slow with the Munica. Please let us know how you are doing your fill.

Peace,Rich

Hi. My initial grain filling was with pumace, and that was applied over two wiped on coats of shellac. After that I started bodying, using just shellac, for 5 or 6 sessions, With a day between sessions. I wet sanded between each body session. Then, I sanded most of that off and grain filled again. Most of the guitar is filled, there are just a few areas and a random pore showing through. The glazing I'm going in a straight line along the grain, using 5 or 6 drops of alcohol and 1 drop of shellac for each pass across the guitar. I'm getting the "haze" behind the munica, but I'm taking away the gloss that was there after the last bodying. I guess I would be happy with abrasive buffing, but I read that glazing produces a deeper gloss. I'll keep trying if it does. Thanks

I have found the real trick to getting a good fill with pumice. Is to not apply any more than a light wash coat(you want very little shellac mixed in during the fill process as this will lead to future sinking/shrinking issues). Really try to get a good even full fill with the pumice. Do small areas till they lood really good then move on. After you have a good fill do another wash coat and give it a day and double check your fill. Don't try to fill with body coats. The shellac just does not do well as a fill on its own, and does very poorly if you get it too thick in spots during a session. After it is really well filled and solid. Then start your body coats, and don't sand. Just keep pushing more coats(again nothing too thick, use high pressure thin coats). After you have almost all your body coats. Then do a level sand(not too heavy). and add one extra session to make sure your good. Then you can move to glazing(again not too heavy on the shellac or solvent, as it will just melt the shellac and screw up all your leveling efforts). My kinda rule of thumb is that if I am applying shellac I use high pressure, and if I am quickly flashing off oil or light glazing I use a little alcohol with quick speed and med. pressure(very fast flash, maybe a 1" tail).

Peace,Rich

P.S. It may be that the gloss you are seeing is the oil on the surface. The haze is probably the product of clearing the oil off the surface. I am not sure if you flash off the oil after every body session, but it is a good idea and will help the shellac cure harder.

Edited March 26, 2007 by fryovanni

[olddog]

Not sure how you are going about grain fill. Are you using pumice or epoxy or??? Sounds like you may be trying to do too much filling with the shellac itself(which shrinks back quite a bit). As far as the glazing. Maybe you are loading a little too much alcohol, or going a little slow with the Munica. Please let us know how you are doing your fill.

Peace,Rich

Hi. My initial grain filling was with pumace, and that was applied over two wiped on coats of shellac. After that I started bodying, using just shellac, for 5 or 6 sessions, With a day between sessions. I wet sanded between each body session. Then, I sanded most of that off and grain filled again. Most of the guitar is filled, there are just a few areas and a random pore showing through. The glazing I'm going in a straight line along the grain, using 5 or 6 drops of alcohol and 1 drop of shellac for each pass across the guitar. I'm getting the "haze" behind the munica, but I'm taking away the gloss that was there after the last bodying. I guess I would be happy with abrasive buffing, but I read that glazing produces a deeper gloss. I'll keep trying if it does. Thanks

I have found the real trick to getting a good fill with pumice. Is to not apply any more than a light wash coat(you want very little shellac mixed in during the fill process as this will lead to future sinking/shrinking issues). Really try to get a good even full fill with the pumice. Do small areas till they lood really good then move on. After you have a good fill do another wash coat and give it a day and double check your fill. Don't try to fill with body coats. The shellac just does not do well as a fill on its own, and does very poorly if you get it too thick in spots during a session. After it is really well filled and solid. Then start your body coats, and don't sand. Just keep pushing more coats(again nothing too thick, use high pressure thin coats). After you have almost all your body coats. Then do a level sand(not too heavy). and add one extra session to make sure your good. Then you can move to glazing(again not too heavy on the shellac or solvent, as it will just melt the shellac and screw up all your leveling efforts). My kinda rule of thumb is that if I am applying shellac I use high pressure, and if I am quickly flashing off oil or light glazing I use a little alcohol with quick speed and med. pressure(very fast flash, maybe a 1" tail).

Peace,Rich

P.S. It may be that the gloss you are seeing is the oil on the surface. The haze is probably the product of clearing the oil off the surface. I am not sure if you flash off the oil after every body session, but it is a good idea and will help the shellac cure harder.

Thanks for the details. From your description I don't think I'm giving enough patience will grain filling. I don't think I filled enough. A couple of questions; Do you do all the grain filling in one session, or do you give some time in between numerous sessions?

I don't think I'm using too much oil. I only add one drop every 4 passes over the guitar, maybe 4 drops in each bodying session. I did spirit off on past projects, I didn't on this one, I will start again.

Thanks again for the info, I'm sure the lightbulb will go on over my head this afternoon, and I'll think; " That's what he means!"

[fryovanni]

Grain fill is done in one sitting(with a good looking over after I wash coat it, and if I need to add fill I continue till it is good). The main thing about pumice as a fill method. Is that you are in a sense sanding the surface and trying to smooth and pick up wood dust to fill the pores. You wind up with some pumice and some wood in the pores. You really want to make sure they are packed full before you apply hardly any shellac. That way you are going to limit the shrink back(as shellac does not fill well at all on its own).

As far as oil. I use whatever it takes to keep the munica moving without sticking. I do spirit off after sessions as it does seem to work well.

Sounds like you are doing good. It takes a while to get everything working smooth.

Peace,Rich