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pumice pore fill for French polish
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Author:  WendyW [ Mon Jun 15, 2015 10:05 am ]
Post subject:  pumice pore fill for French polish
For those of you who pore fill with pumice when french polishing, I'm interested in hearing your method and materials. I already have 3 spit coats of shellac on. Some say pumice and alcohol only at this point, which is what I have done in the past. Some people use additional shellac, and some people add oil. What do you use?
Thanks, Wendy
Author:  jfmckenna [ Mon Jun 15, 2015 10:20 am ]
Post subject:  Re: pumice pore fill for French polish
I just use alcohol at that point. The shellac is already down now you want to mix it up into a slurry of sorts so it only requires alcohol. I don't think using oil would be a good idea at this point either. The idea now is to use the pumice as an abrasive. Think of it more of using an abrasive to fill the pores with saw dust rather than filling the pores with pumice. The shellac you laid down is going to act as the binder for the dust you scrape of the wood with the pumice. When you do it right it feels and sounds more like sanding.
Author:  Bryan Bear [ Mon Jun 15, 2015 10:45 am ]
Post subject:  Re: pumice pore fill for French polish
What he said ^^^^

I haven't used shellac at this stage but would expect it to make it too sticky. In fact, I find that less alcohol and less pumice work better than more. I would think oil would inhibit the grinding action of the pumice a bit. I'm not sure what it would look like when the oil came back to the surface after you stop; but it would probably mean you need to do more filling.
Author:  Michael.N. [ Mon Jun 15, 2015 10:53 am ]
Post subject:  Re: pumice pore fill for French polish
It also tends to wear holes in the cloth. If it doesn't it may mean that things aren't working too good.
You could also try (on scrap) sprinkling the Pumice directly onto the wood and pushing it with your palm into the pores. Then you need some Danish Oil (preferably the stuff with a resin content). Drizzle that on top and push it around to fill the pores. The Oil clears the pumice. After an hour or so scrape off the excess, going across the grain. A couple of days later it needs to be repeated. You can French Polish on top of that if you get rid of the excess sitting on the surface. One of the easiest and more 'natural looking' methods of pore filling IMO.
Author:  Greg B [ Mon Jun 15, 2015 11:02 am ]
Post subject:  Re: pumice pore fill for French polish
It depends on how much shellac you laid on with the spit coats, but generally speaking alcohol and pumice only at this point. However, if things are getting too powdery due to lack of shellac, it's ok to add a drop or two of shellac to the pad.

Using any oil at all in this technique is a bad idea, IMHO. It will slowly seep out of the pores and cause issues later. (I can imagine danish oil would work though, if you must use oil at this point. It dries... )

That said, 'true' french polish pore filling is done with oil and pumice or other filler only -- no shellac. This is a entirely a different technique though. It's used on furniture but not (typically) guitars.
Author:  Greg B [ Mon Jun 15, 2015 11:49 am ]
Post subject:  Re: pumice pore fill for French polish
Michael.N. wrote:
You could also try (on scrap) sprinkling the Pumice directly onto the wood and pushing it with your palm into the pores. Then you need some Danish Oil (preferably the stuff with a resin content). Drizzle that on top and push it around to fill the pores. The Oil clears the pumice.


After reading this again, I realize you are describing the original FP pore filling technique. Different ways to do it, but basically a slurry of pumice and a drying oil or varnish is rubbed into the pores. The nice thing about this is that it pops the grain more than shellac/pumice. Probably it was not used historically by luthiers much of the potential for the oil's effect on damping/deadening.

Probably better to pick one or the other: shellac & pumice, or oil/varnish & pumice -- and stick to it.
Author:  Michael.N. [ Mon Jun 15, 2015 12:29 pm ]
Post subject:  Re: pumice pore fill for French polish
Depends what you call the 'original method' of French Polishing. I'm sure that there were quite a few that developed roughly at the same period.
I know the Oil method but what I'm describing is slightly different. In any case there is nothing to stop someone putting on a a couple of spit coats of shellac, allowing it to dry and then using the Oil/Pumice fill. I just put it straight on to wood because . . . I want the Oil on wood.
Author:  DennisK [ Mon Jun 15, 2015 1:00 pm ]
Post subject:  Re: pumice pore fill for French polish
It doesn't really matter how much shellac is spit coated on versus how much you put on the pad. When you apply alcohol to the spit coat layer, it will dissolve. The important thing is that you have the right amount of shellac total. Spit coating is just convenient because it supplies shellac as you go, and helps reduce staining of light colored areas by the extracts from dark woods. If you have too much shellac involved while pumice filling, it will fill up the pores and then shrink when it dries. Also, a thick and dry shellac layer can block you from grinding up actual wood dust with the pumice for a while until it dissolves and/or is ground up itself.

Lately I've been doing it as a two pass process. First sand with 220 grit wet/dry paper and alcohol to quickly form the shellac/wood dust slurry, then switch to pumice on a pad (fairly wet with alcohol) to work it into the pores. The sandpaper doesn't seem to ever top off the pores, but it does give you a good head start and saves a few pad covers.

Go in circles with the pad to "activate" an area with alcohol, and then push in slow straight lines to really move the slurry around and pack it into the pores. I don't think it really matters what direction you go relative to the grain. If you go too fast or the pad is too dry, the slurry won't dissolve enough to move. And without pumice, the pad doesn't grip the slurry to drag it.

I don't use any oil.
Author:  JSDenvir [ Mon Jun 15, 2015 5:05 pm ]
Post subject:  Re: pumice pore fill for French polish
And just to confuse the issue... :-)

I ran into a fellow named Barry Gork at ASIA. A South African, now in Chicago, he is the proprietor of goodfilla.com

He currently has coloured pore fillers, and a new clear one will be available in a month from Stewmac.

Apparently, this stuff is incredible. The consistency of yogurt, it will pore fill a back and side in one coat. Possibly two for really porous woods like white oak. It's dry enough to sand in 15 minutes. (Take that, ZPoxy!)

The really good news? Say you discover a void or two after the first couple of coats of finish? Just fill it with this stuff.

I'm not that familiar with spraying finish, I'm a French polish guy, but according to Sylvan Wells, this stuff is the real deal. He's used it on 6 guitars so far and hasn't had any issues.

I'm looking forward to trying it. And fwiw, Barry seems to be a really good guy. It'd be nice to see him win.

Steve
Author:  kencierp [ Mon Jun 15, 2015 5:38 pm ]
Post subject:  Re: pumice pore fill for French polish
I'll be getting some the "New Clear" PF from SM for testing, its in the latest catalog -- I've heard this before, all the way back from when Hydro-coat was introduced, every one had/has silica and every one got/gets cloudy after three coats. If the expectation is that 100% sand back is required -- well that is a PITA. I am looking for clear transparent like Zpoxy which can be left on the surface. My hopes are high - we'll see.
Author:  jshelton [ Mon Jun 15, 2015 5:42 pm ]
Post subject:  Re: pumice pore fill for French polish
JSDenvir wrote:
And just to confuse the issue... :-)

Apparently, this stuff is incredible. The consistency of yogurt, it will pore fill a back and side in one coat. Possibly two for really porous woods like white oak. It's dry enough to sand in 15 minutes. (Take that, ZPoxy!)

Steve

Sorry to burst the bubble but Goodfilla is just another pore filler that doesn't work well at all. I could never get the pores filled after many applications. I'm back to using z-poxy which DOES work.
Author:  JSDenvir [ Mon Jun 15, 2015 6:08 pm ]
Post subject:  Re: pumice pore fill for French polish
Hey John, I don't know if the clear stuff is different, but it's just becoming available. And, as I said, Sylvan Wells, after 6 guitars, is quite pleased with it. I'm looking forward to trying it myself.

Steve
Author:  jfmckenna [ Tue Jun 16, 2015 7:13 am ]
Post subject:  Re: pumice pore fill for French polish
FWIW I don't use pumice anymore. I use egg whites. Not only does it do a quick and fantastic job but my customers are typically the type that really dig the fact that I use eggs to finish their guitars :)
Author:  Eric Reid [ Tue Jun 16, 2015 11:53 am ]
Post subject:  Re: pumice pore fill for French polish
No oil, no eggs, and sometimes no spit coat. If the wood is very resinous like cocobolo or some Brazilian rosewood, the resins of the wood will be sufficient binder for the pumice. You need to have enough shellac or resin saturating the pumice to make it dark and translucent. Too little binder, and you end up with light colored pores. Too much binder, and you get sticky blobs of pumice on the surface, and if there is figured grain, you risk trapping air in the pores. The air will bubble up as you progress with the finish, and there's no remedy other than going back to bare wood. The only way to judge how much shellac you need while pore filling is by monitoring the consistency of the pumice slurry. I don't think this skill can be communicated without a lot of hands on experience. What woods are you finishing?
Author:  Eric Reid [ Tue Jun 16, 2015 12:10 pm ]
Post subject:  Re: pumice pore fill for French polish
Greg B wrote:
That said, 'true' french polish pore filling is done with oil and pumice or other filler only -- no shellac. This is a entirely a different technique though. It's used on furniture but not (typically) guitars.


I agree with Michael that there are a lot of very different, and equally old techniques. The pumice and shellac pore fill that I do is very similar to the one Tage Frid learned as an apprentice furniture maker in Denmark. He stresses no oil in the pore fill. I know others use oil. In some early accounts the pores are filled with plaster. Epoxy pore fill can't claim to be part of the history, but several builders now use it for their French polish. Sometimes the term "French polish" is used to describe synthetic sprayed finishes as well. And a thin coat of shellac is sometimes sprayed over synthetic finishes to create a "French polish."
Author:  WendyW [ Tue Jun 16, 2015 2:50 pm ]
Post subject:  Re: pumice pore fill for French polish
I finally got a chance to get back here and see there are a lot of responses.

Eric, I am finishing some very porous figured honduran mahogany. Getting ready to start pore filling this weekend after having put 3 "spit coats" of shellac on the guitar on Sunday.

I have pore filled with pumice and alcohol in the past. I was just curious because I saw 2 references to adding either shellac or oil to the pad. Can't remember where I saw it but one was from Eugene Smith and the other was from Cyndy Burton and I was surprised.

Dennis, I tried something similar to your 2 pass method on a scrap last weekend, but I did it in reverse. First pumice, then another shellac coat, then 320 wet/dry with alcohol. I was surprised how much faster the 320 filled the pores than the pumice method. The only problem was I felt like the 320 left scratches and it clogged very quickly. Maybe 220 would be better. I was sanding in small circles and when I was done, the scratches sanded out easily. Are you sanding with the grain?
Author:  WendyW [ Tue Jun 16, 2015 2:52 pm ]
Post subject:  Re: pumice pore fill for French polish
I should clarify that on the scrap last weekend, I first put a few coats of shellac, then filled with pumice on a pad cleared with alcohol. Then later, another coat of shellac, and when that was dry I used the sandpaper with alcohol.
Author:  DennisK [ Tue Jun 16, 2015 3:43 pm ]
Post subject:  Re: pumice pore fill for French polish
callyrox wrote:
Dennis, I tried something similar to your 2 pass method on a scrap last weekend, but I did it in reverse. First pumice, then another shellac coat, then 320 wet/dry with alcohol. I was surprised how much faster the 320 filled the pores than the pumice method. The only problem was I felt like the 320 left scratches and it clogged very quickly. Maybe 220 would be better. I was sanding in small circles and when I was done, the scratches sanded out easily. Are you sanding with the grain?

I go in circles. The second pass with pumice should remove the scratches.

Oh, and I use an artgum eraser as a sanding block. Rounded on one side to get into the waist, and all edges softened so the paper doesn't get creased sharply. Both to reduce clogging, and to reduce the chance of grits falling off and getting trapped in pores, which might be visible on light colored woods. But I mainly have trouble with clogging when sanding dry (which I only do when trying to fix mistakes). Try adding alcohol more often and/or in larger quantity and see if that keeps the paper clear.
Author:  WendyW [ Tue Jun 16, 2015 4:54 pm ]
Post subject:  Re: pumice pore fill for French polish
Thanks Dennis. After you do the first pass with the sandpaper, do you put any more shellac on and let dry before doing the pumice, or do you go right into the pumice.
Author:  DennisK [ Tue Jun 16, 2015 5:34 pm ]
Post subject:  Re: pumice pore fill for French polish
Nope, just alcohol and pumice on the pad. But if there's one thing I've learned about French polishing, it's that you have to have to be adaptable. It never seems to work exactly the same way twice. If it seems like you need more shellac, add more shellac.
Author:  Eric Reid [ Wed Jun 17, 2015 12:19 am ]
Post subject:  Re: pumice pore fill for French polish
callyrox wrote:
I finally got a chance to get back here and see there are a lot of responses.

Eric, I am finishing some very porous figured honduran mahogany. Getting ready to start pore filling this weekend after having put 3 "spit coats" of shellac on the guitar on Sunday.

I have pore filled with pumice and alcohol in the past. I was just curious because I saw 2 references to adding either shellac or oil to the pad. Can't remember where I saw it but one was from Eugene Smith and the other was from Cyndy Burton and I was surprised.


Maybe Eugene Clark? I understand that Cyndy Burton uses an epoxy pore fill. Maybe I'm wrong about that.

Mahogany should give you no troubles. Finishing a Spanish cedar, or mahogany neck is always the easiest part. The pores fill easily, and the blonde wood hides any light-colored pores. I smile when I see some new pore-filling scheme demonstrated on the neck.

Tage Frid's explanation in his Fine Woodworking volume is still the best I've seen on French polishing. Read that, and practice on scraps for a few months, and you're ready to start.

I don't know anyone who achieved a good finish in their first 50 guitars. I know I didn't.

At this point, I've handed my finishing work off to a woman who has French polished over 1,000 guitars. We still consult about finishing problems. She agrees: you're never done learning. She laments daily about problematic wood.

The good news, with a seasoning of sexism, is what I was told by the Paracho guitar finisher that I studied under: "Women can learn to French polish. A few men can--most can't."
Author:  Eric Reid [ Wed Jun 17, 2015 12:28 am ]
Post subject:  Re: pumice pore fill for French polish
DennisK wrote:
Nope, just alcohol and pumice on the pad. But if there's one thing I've learned about French polishing, it's that you have to have to be adaptable. It never seems to work exactly the same way twice. If it seems like you need more shellac, add more shellac.


Dennis has this absolutely right.
Author:  WendyW [ Wed Jun 17, 2015 9:28 am ]
Post subject:  Re: pumice pore fill for French polish
Eric, the reference to Cyndy Burton was a quote from a demonstration she had done many years ago and she may very well be using epoxy now. The honduran mahogany I am filling is the back and sides and is quite dark in color actually. I usually don't pore fill my necks and this one happens to be maple, so no need anyway. Strangely enough, the first guitar I ever French polished came out beautiful and I have never been able to repeat that. It may have been a fluke, but on that first one I followed the older Milburn tutorial very closely and was very happy with the results. On subsequent ones I have varied the technique and tried other suggestions, and the results have never been as good. This time, once I get through the pore filling portion, I am going to go back and follow that tutorial again and see what happens.
Author:  GoodFilla [ Wed Jun 17, 2015 4:24 pm ]
Post subject:  Re: pumice pore fill for French polish
jshelton wrote:
JSDenvir wrote:
And just to confuse the issue... :-)

Apparently, this stuff is incredible. The consistency of yogurt, it will pore fill a back and side in one coat. Possibly two for really porous woods like white oak. It's dry enough to sand in 15 minutes. (Take that, ZPoxy!)

Steve

Sorry to burst the bubble but Goodfilla is just another pore filler that doesn't work well at all. I could never get the pores filled after many applications. I'm back to using z-poxy which DOES work.


Mr. Shelton, perhaps I could interest you in trying both the paste and the Clear GoodFilla products again? It seems there may have been a process issue. And don't take my word for it, take Sylvan Wells' and Tom Anderson's word (AndersonGuitars.com)

Barry
Author:  kencierp [ Wed Jun 17, 2015 4:46 pm ]
Post subject:  Re: pumice pore fill for French polish
Barry --- conceptually is this product (Goodfilla Clear) supposed to be sanded back so that, other than the material in the pores it must be all removed prior to next step-- be that sealer or what ever?

Thanks
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