French Polishing

[Donald A. Fortune]

I"m in the process of making a dred. and I'm looking for info on the french polish system.
I have already put on 24 spit coats and I've sanded with 400 grit in between every 6 coats.
Now here's my boggle -- I still haven't filled all the pores. how many coats are necessary to do this?
I saw a product called "Z-POXY" in LMII's cat. and it claims that it can be thinned with alcohol,
and was wondering if any one has had any experience with this product..
Any feed back will be appreciated----
Peace,Donald

[Greg Mirken]

Donald, what wood is this? How do you want the pores to look? What exactly is a spit coat, and how have you applied these? Spitting? :P

[Donald A. Fortune]

Hi Greg my wood is zebra wood and it is an open pore hard wood. I want it to be completely "flat" when I am finished. A "spit" coat I would say is another way of saying a coat of shellac.
Seems like the shellac by it self is not filling the pores the way I expected, I mixed it 50/50 with alcohol
to make it as thick as possible and it just isn't doing the job. HELP??
Peace, Donald

[Ned Knepp]

I've found that French polish will fill the grain, at least on mahogany, but it takes a LOT of time/coats. I had to sand most of the finish off between sessions until the pores were filled or I just end up building a thick coat with pits. I had to build up the finish, let it set overnight then sand almost all of it off before building more finish. I did this many times before the finished finally leveled out. Along the way, I realized that I would have saved a lot of time if I had filled the grain with a filler first.

I'm not sure that making the shellac "thick as possible" will gain anything for you. I'm not nearly expert at this but I've found that thinner shellac builds better because the alcohol flashes off faster. I tend to gum up with thicker mixes but the thinner mix allows me to pretty much polish until I decide to stop. It's a lot of thin layers but I think I have a harder finish this way.

Ned

[Randall Curtis Bowman]

This method works great. Even on open-grained red oak. I've used it on walnut, too. Good luck.
http://www.milburnguitars.com/fpgraincontents.html

[griff]

A spit coat is really just the first sealing coat. Usually it's applied with a brush on the bindings, rosette, or any place where different woods join to help avoid bleeding from dark woods to light (notoriously rosewoods will bleed into spruce), and then generously applied in larger areas with the pad. The process you're describing is called building, which is layering the coats to build enough base to fill pores and rub out. Trying to fill pores using the shellac only will take forever. Traditionally, and probably the best method, is to use super fine pummice powder to abrade the wood, shellac and pummice into a slurry that will fill pores. I have also used varnish to fill and build, and then french polished over that...that works very well. I think the z-poxy stuff is basically bondo...it will work like an epoxy coat to fill, though I've never used epoxy to fill.

[Greg Mirken]

If you want the filled pores to be clear, in other words you want to see into the pores, I think your best bet is a clear epoxy. Smoosh it on and scrape the surface clean with a flexible nylon auto-body squeegee.

[Donald A. Fortune]

Thanx Greg I am doing a practice thing on some of the back wood that is a drop from cutting out the profile of the guitar. I think I will order the filler from LMII and give it a try and see where it goes from there .
Peace, Donald

[David Houchens]

Ihave tried sealing pores with the pumice method on natural wood before, but what do you do if you want to stain the wood? I have always stained my mahogany. Won't this method cut into the stain?

[Donald A. Fortune]

Hi Dave I don't get into staining any of my wood that I make guitars out of- If anything they may be done with a toner in lacquer or poly and or I may use a darker shellac and it has always worked out for me
Peace, Donald

[Mark McLean]

I think there are 2 issues to consider in approaching pore filling:
1. What is the best method to fill pores in hardwood and get a nice smooth finish, with minimum work/time/toxic chemical exposure?
2. Why do we bother to even do this?

On question 1 I have a modest amount of experience (only build 3 guitars), but I have done a lot of reading
Regarding question 2 I have formed a firm personal opinion and when I tell you about it I may start ranting (please feel free to disregard it all).

Question 1
The traditional method is to use an abrasive mixed with some sort of finishing compound and to raise fine dust from the timber and get it to seep into the pores together with something which will make it stick there. Variations on this theme are pumice (the abrasive) plus shellac, wet sanding (eg 400 grit) plus shellac, wet sanding plus egg white, wet sanding with an oil/varnish (eg Tru-oil or Danish). It may take a number of applications and sanding back to bare wood each time. Pumice is traditional but it can leave white spots in the pores of dark wood. I have heard good reports of egg white but I haven't tried it myself.

The modern method is to take a thin industrial adhesive which dries clear and to apply it all over the timber so that it fills the holes and covers the whole surface, sand back to bare wood and it will then look smooth. Epoxy (like Z-Poxy, or West Systems) or cyanoacrylate (superglue) are the most commonly used. I have tried both and they are pretty quick to apply and do a reasonable job at filling. The downside is the tough sanding job to get them back to bare wood, the major stink as you smear them all over your guitar, and the nasty toxicity that can result from the dust (especially epoxy). They also change the texture of the wood (it becomes a lot harder and more rigid) and I don't know what that does to the acoustic properties. Z-poxy is also rather dark coloured and may darken a pale wood, like maple.

But turning to Q2
Why are we so sold on pore filling anyway?
It was Bob Taylor who said, "A long time ago, some guy figured out that if you keep spraying and sanding a guitar, you can make it really shiny. We need to exhume that guy and shoot him!" Most guitar buyers now think that an instrument should have a finish that looks like a pane of glass, and most guitar builders keep delivering that product. It is not really necessary, and it is probably acoustically bad. Other instrument makers and players don't have this fixation. When did you ever see a violin or a cello with a nitro finish? I actually like a guitar with a finish that doesn't get between you and the real wood. I think that an oil or shellac finish with open pores, or minimal pore filling, is more beautiful than a smooth gloss finish. I currently also have a Taylor and a Martin with open pore satin finishes (both “low-end” models) and they are great looking instruments (IMHO). This kind of finish is easier, more repairable and more ecologically friendly. Sure, if I was trying to make a living selling my guitars I would probably go broke because that is not what the market wants. But maybe we should educate the buyers. As long as I am making guitars for myself or friends my plan is to use oil finishes with wet sanding of the first couple of coats to fill the deepest pores, but I leave a satin textured finish at the end (using 0000 steel wool). But each to their own. If someone asked me for a gloss FP finish I would probably try the egg-white method (as always, test first on scrap) - at least you can make an omelette with the yolks
OK, I will get down from my hobby-horse now.............
cheers
Mark

[Donald A. Fortune]

Good thoughts Mark--- I'm an old cabinet maker (not to be confused with a cabinet maker that is old)
and somehow I like the natural look of grane and this glass type finish is getting me down.
thanx for the comment ---
Peace,Donald

[Rick Gentry]

I like your post and agree with the shiny thing. Personally I abhor a glass like finish, but that seemed to be the only choice until I started buying old patina-y guitars. My Frankenstein Tele and Strat have mahagony bodies with nothing but boiled linseed oil, and the jewel tone that finish gets after a couple years of human touch is beeautiful. Once in a while I will convince a cabinet customer that a BLO finish is better than polyurethane, and will look so much better over time. Here is a shot of desk with oil that is still a little wet.

The satin line of PRS et al is stretching into this area, but I would be hard pressed to ever buy a new guitar again. There are so many others that need a good home.