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I spent hours today practicing pumice filling a sample of very figured porous mahogany. It took forever and, despite the fact that I cleared the pumice I ended up with some white in the grain in a few places. It also took forever to get the pores filled.

At the end of the day, on a whim, I made a slurry of shellac and pumice about the thickness of cream. I took another sample that had been sealed with shellac and applied the slurry with a piece of t-shirt, in circular motion as if I was applying paste wax. The pores filled immediately. When it was dry I sanded with 320 and then did a couple of french polish sessions. I could not tell the difference from the sample I spent hours on. The only difference was the shellac/pumice slurry one had no white in any of the grain and actually looked better.

So, this is too easy and I know there has to be a good reason people go to the trouble to do it the traditional way. Please educate me! Quickly, before I do this to my guitar.
Wendy

Interesting. I would have thought pure pumice would look weird without getting wood dust ground up with it. Give it a day or two and see if it shrinks much from the high shellac content. Could get some tests going on other woods too, and see if it only looks good on mahogany, or works for rosewoods and such too.

After starting my last pore fill with pumice and being severely frustrated, I switched to egg white.

This was to fill very open grained wenge. A couple of coats of egg white left to dry, then sanded with wet and dry slightly dampened.

Using egg White was a revelation and it was so effective I can't see a reason to go back to pumice.

Try it on different wood types. Don't forget it's not just about filling open pores, you want a 'natural' looking colour match too.
Give your Shellac slurry a few weeks, see how it looks then. You might find that the white pores come back to haunt you, it will certainly shrink though and you will need to repeat the process. What you describe is similar to the Oil/Pumice slurry method. I sprinkle Pumice directly on to the wood surface and push the pumice into the pores with the palm of my hand. A thin Oil varnish (Danish or Tru Oil) is drizzled on top and I work the slurry into the pores. Excess is removed with a credit card, after 30 minutes or so. After a few days it will need repeating too, although the process isn't very time hungry.

I just tried colored drywall compound on very open oak pores on the advice of Brad Goodman. Very easy to do and works well. Apply as usual, credit card, etc, let it dry normally or speed it up with a hair dryer and you can put on a second coat in a few minutes. Very easy to sand and effective in filling.

I will give the pumice method and the egg white method a shot - if it will fill oak, it will fill anything.

Ed

There are plenty of ways that work to fill in the pores, silica (dry wall compound and commercial fillers) pumice, egg whites, wood flour, saw dust and finish material usually shellac, hide glue etc. I see two main concerns with all these methods. The contrast -- what color is going to be left in the pores? Sometimes it ends up way too light which can be a real mess. The second issue is the sand back, if the slightest bit of material is left on the surface under top coats it will show up as a blotch or visual defect of some sort.

So for me this is problematic and why I recommend Zpoxy, With it, the pores are filled with an almost transparent medium which in my view enhances the surface. Perhaps more importantly the last step in Zpoxy application (at least how I do it) is to wipe the surface with alcohol, this creates a thin film of material over the entire instrument -- thus no witness lines, no unevenness, no blotches. And I find it very easy to use -- disposable vinyl or nitrile gloves are a must.

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Ken Cierp

http://www.kennethmichaelguitars.com/

Dennis, When I mixed the pumice with the shellac, it cleared, and the slurry looked like a thick blond shellac. Also, according to the Milburn french polish tutorial, you can go back and pumice missed pores after numerous body sessions, when I don't think the pumice would be actually contacting the wood?

Michael and Dennis, How long do you think I should wait to see if it shrinks and needs to be repeated? And are you saying that the color could change with time, even though it looks clear now?

You can mix pumice into egg whites too- I did a few test panels recently and it worked great. I made the slurry and then applied with 320 so there was at least a little wood dust mixed in. 2 months later and it still looks nice and flat.

After experiencing some dermatitis from epoxy I never want to have to sand it again! Especially if something else works.

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Burton
http://www.legeytinstruments.com
Brookline, MA.

It's possible but then again it might be perfectly fine. Sometime in the long distant past I've done exactly the method that you have used but I honestly can't remember the outcome. I obviously didn't continue with it, for whatever reason. You are doing the experiment now, so you may as well see how it turns out. Sometimes a method will work OK on one type of wood but you might not get a great colour match on another type. That happened to me with the egg white sand method and Walnut. It was a bit of a disaster but it worked fine on Rosewood. It's just a matter of finding a filler/method that you are happy with and that suits you.
I'd give your Shellac/Pumice it at least a week and see if it needs repeating. It's not a disaster if it does need repeating, most pore fillers do. If it's quick to apply it's no big deal.

"Perhaps more importantly the last step in Zpoxy application (at least how I do it) is to wipe the surface with alcohol, this creates a thin film of material over the entire instrument -- thus no witness lines, no unevenness, no blotches. "

Could you expound on that? I have always wiped on a thinned coat of zpoxy for the last coat. Are you saying that you can simply wiped the dried zpoxy with alcohol?

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Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

I had the same experience you did about 5 years ago then i heard about egg whites.. Egg whites is the only thing I use now not only because it works great but because... Egg whites.

Yes -- but not fully cured (like days), and this is "minor feathering" of what might be a little sand through. The thinned Zpoxy works well and is a good idea for the last coat. Avoiding top coating on bare wood of course is the goal. I know there are some that sand off every speck of Zpoxy except what's in the pores -- That's too much work for me.

I should mention that I am by no means a finishing expert, I always fall back to nitro and only in the pass couple of years started using Zpoxy as a pore filler.

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Ken Cierp

http://www.kennethmichaelguitars.com/

My guitar has 3 spit coats of shellac on it. Does eggwhite have to be used on bare wood, or can it be used on top of shellac and sanded in with 320? I would think I would have to sand the guitar back to bare wood before doing an eggwhite fill?

I think egg white works best on raw wood. I really don't know about after spit coating with shellac.

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Waddy

Photobucket Build Album Library

Sound Clips of most of my guitars

I tried egg whites once and didn't like it but I can't remember exactly why. I must admit that I had no real plan and it was most likely a technique issue. I think I just tried to wet sand the surface with egg whites and sandpaper. I'm pretty sure it was the mess I didn't care for. Can anyone point me to some directions or a tutorial on it. I really wanted to like it.

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Bryan Bear PMoMC

Take care of your feet, and your feet will take care of you.

There's not a lot to it. You have to seal whatever inlays you have first. Don't sand over the inlays, just close to them and push the slurry into the pores with your fingers. The rest of the wood can be filled by applying egg white and sanding over it. Put some of the solution on to the wood and dip the abrasive into it as well. I think I used 240G. You can beat the egg white but it's not necessary. As far as I can tell it just makes it a little less stringy. Egg White doesn't exactly pop the grain too well so try to get it in the pores and not 'floating' on the surface. Partly why I don't use it anymore.

I have only ever French Polished my guitars, mostly using the pumice fill method, but also with a few experiments with things like Timbermate. Here is how my view of the pumice method sits right now:

Like a lot of folks, I used to think of the pumice method being about filling the pores with pumice, some fine wood dust (created by rubbing the pumice on the wood), and shellac (re-activated by the presence of alcohol in the pad used to rub the pumice, and the abrasive action of the pumice).

Now, however, I think I had it slightly wrong before. I now think that the pumice is there to act mainly as the abrasive, not the filler. The filler should mostly be the fine sawdust and shellac, with just a little of the pumice (i.e., just the amount of pumice it took to cause abrasion to occur, and no more). In other words, the pumice is a bit of a necessary evil; you need it for abrasion more than you need it for filler. It is OK if there is a little of it in the mix, but if there is too much of it, the color of the pumice is visible, and you get specks.

If I am right about this, then the method of filling pores that Robbie O'Brien recently put in one of his videos might be a good way to go. You create some species-appropriate sawdust separate from the guitar, gather it up, then use it as the only filler, along with shellac. No pumice to cause white specks, and color matching is as good as you will ever get.

I'm no expert, but this is something I want to try on the two guitars I currently am building. It sounds promising.

For those who want to stick with pumice, maybe the above way of looking at things helps the standard advice ("don't use too much pumice!") make more sense. It was a bit of an "ah-ha" moment for me.

If the pumice is just abrasive why not use sandpaper?

The pumice method works fine for folks who get the hang of it and, by the way, I agree with Don's excellent post above.

What I wanted to add though is though the years on this forum and others many folks have struggled greatly with the pumice method (it's possible I am sure to struggle with any method..) and in some instances I've read posts where folks were at their wit's end over it.... So be warned, take you blood pressure medicine... it can be humbling.

I've done it and found it to be more difficult than epoxy finishing resin (note health considerations mentioned earlier in the thread). Shrinkage even though a problem for George on Seinfeld is not an issue with epoxy IME and what I see is what I still get a month down the road. That's not my experience with shellac and pumice, it can be a long drawn out process with some shrinkage weeks later. Likely not a great method for impatient and intolerant sorts like me....

There is a recurring theme in Lutherie as to why folks did what they did say back in the day and the recurring answer seems to always be - because it's what they had. These days we have far more choices as to how to go about ruining our instruments....

I'll add too that both french polish and pumice fills are very much an art all unto themselves and the folks who have it right get superb results that glow and show!

Again, I'm not an expert or a historian, but here is what I think:

This is a relevant question in today's world, when we have sandpaper in all sorts of grits and different backing materials, but historically, when the pumice method was used, perhaps it was because they didn't have sandpaper. At least not like we have it today. If you wanted to finely abrade or polish something, you rubbed pumice on it.

This thread from the UMGF has given me a lot to think about and I've gone back to it a few times:

http://theunofficialmartinguitarforum.y ... Zr13OtH0fF

I don't think the pumice is just abrasive- It adds something to the mix that will NOT shrink back - I think that is important. The above thread gets into that a bit.

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Burton
http://www.legeytinstruments.com
Brookline, MA.

Burton--

I think the problem with that way of thinking about the pumice is that, if you do it right (i.e., with just the right amount of pumice), the white/grey color of the pumice does not show. Why? Because there is a whole lot of sawdust and just a little pumice in the pores. If you use too much pumice (whatever that amount is), the white/grey color of the pumice shows up as specks in the pores. I hate to admit why I am so familiar with this phenomenon. My point is, there is so little pumice in the pores of a good pumice fill job that I doubt it helps that much with shrink back.

Contrast that with filling with drywall compound, or some other mineral. The pores are filled with just drywall compound that has been colored to match or be darker than the wood. No shellac, no sawdust. There is some shrink back due to the evaporation of the water in the compound, but a second coat and careful removal of excess can fix that.

I see these as different methods.

I asked myself the same question, and then tried it, described in the previous pumice thread http://www.luthiersforum.com/forum/viewtopic.php?f=10101&t=45885. It works well as a head start, but a pumice pad is better at dragging slurry around and leveling off the pores.

Burton, Thanks for the link, interesting stuff. I knew pumice was volcanic rock but for some reason I never made the connection. Wendy

Don, when I dissolved the pumice in shellac it left no residue of color in the pores at all, unlike when I try to pumice fill in the traditional manner of using a pad and clearing the pumice with alcohol. With that method I seem to always end up with a few places where there are white specks, no matter how careful I am to clear the pumice. This was just pumice and 2#shellac mixed together. Got the same effect as using a clear pore filler.