Official Luthiers Forum! :: View topic - Possible Issue Pore Filling With Pumice

My method may be totally wrong, but when I pore fill with Pumice, I use a muneca that has been prepared for French polishing. That is, one that has been soaked in shellac then squeezed out and allowed to dry overnight. The places where I have gotten light splotches have always been in areas where I concentrated too much. I think when you start bodying the darker spots will go away. I think! idunno

Something else I recently discovered is to make a pounce with my pumice and a square of the muneca covering material or a piece of T-shirt which is not a good muneca covering material, but I tie a couple of table spoons of shellac up and instead of using a salt shaker, I tap the pounce on my muneca. It leaves a light coat of shellac on the surface. I clear it with alcohol and work the area. It seems to cut down on the clogging up.

I don't plan to FP the back and sides and neck they will be sprayed. I may lay down a base coat of FP just to clean up the surface a bit and add some layers to fine sand before spraying. I really wanted a more durable surface there.

The fill looked great.

Yeah, I agree that some shellac is needed to get the pores to fill well. I always thought Milburn used a prepared muneca, but did not add shellac while pumicing. Is that a word?

Thanks, I'll give it a try.

Any thoughts Waddy on whats causing the white spots? (have you seen them at all on any of your EI rosewood?)

Nate Swanger wrote:

Thanks, I'll give it a try.

Any thoughts Waddy on whats causing the white spots? (have you seen them at all on any of your EI rosewood?)

How humid has it been while you've been applying the polish?

Moisture trapped in between thick layers can look exactly like that.

Author:	Nate Swanger [ Mon Sep 27, 2010 7:43 pm ]
Post subject:	Possible Issue Pore Filling With Pumice
Have a quick question, Started poor filling this past weekend with pumice. Did 3 coats of shellac first then started to pore fill after letting it sit a day. pore filling was just some pumice cleared on a doll with denatured. Noticed some areas are getting "light spots" around the filled pores not sure why just some areas and not the rest. Also the over all coating seems thick to me, but this is my first attempt so i wanted to get some feed back. Also makes the whole shellac coating look cloudy, should this be the case? the Milburn toot doesn't show any cloudiness on his pictures. Could i be using too much pumice, or too much denatured? any advice would be appreciated, Nate

Author:	WaddyThomson [ Mon Sep 27, 2010 8:12 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
My method may be totally wrong, but when I pore fill with Pumice, I use a muneca that has been prepared for French polishing. That is, one that has been soaked in shellac then squeezed out and allowed to dry overnight. The places where I have gotten light splotches have always been in areas where I concentrated too much. I think when you start bodying the darker spots will go away. I think! Something else I recently discovered is to make a pounce with my pumice and a square of the muneca covering material or a piece of T-shirt which is not a good muneca covering material, but I tie a couple of table spoons of shellac up and instead of using a salt shaker, I tap the pounce on my muneca. It leaves a light coat of shellac on the surface. I clear it with alcohol and work the area. It seems to cut down on the clogging up.

Author:	Nate Swanger [ Mon Sep 27, 2010 9:09 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
WaddyThomson wrote: My method may be totally wrong, but when I pore fill with Pumice, I use a muneca that has been prepared for French polishing. That is, one that has been soaked in shellac then squeezed out and allowed to dry overnight. The places where I have gotten light splotches have always been in areas where I concentrated too much. I think when you start bodying the darker spots will go away. I think! Something else I recently discovered is to make a pounce with my pumice and a square of the muneca covering material or a piece of T-shirt which is not a good muneca covering material, but I tie a couple of table spoons of shellac up and instead of using a salt shaker, I tap the pounce on my muneca. It leaves a light coat of shellac on the surface. I clear it with alcohol and work the area. It seems to cut down on the clogging up. Thanks, i doubt there is a wrong way as long as it comes out thin, hard and clear. The tutorial that i was fallowing however recommended against both of those. and since im not much for experimenting when trying to learn basics i stuck with it as closely as possible. http://www.milburnguitars.com/fpbannerframes.html i did three spit coats of shellac rubbed on with a piece of clothe before i started polishing with just denatured. I did work the area with the "light spots" around the pores a good bit with a decent amount of denatured. Now I'm mainly concerned that it will show up once i throw down a coat or two of nitro. If it will, I am not quite sure how to fix it, it looks like its right in front and behind the pore. I don't plan to FP the back and sides and neck they will be sprayed. I may lay down a base coat of FP just to clean up the surface a bit and add some layers to fine sand before spraying. I really wanted a more durable surface there.

Author:	JohnAbercrombie [ Mon Sep 27, 2010 9:35 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Nate Swanger wrote: I don't plan to FP the back and sides and neck they will be sprayed. I may lay down a base coat of FP just to clean up the surface a bit and add some layers to fine sand before spraying. I really wanted a more durable surface there. One possibility (instead of nitro) would be using U-Beaut Shellac(from LMI) which you can pad on like FP. It's reputed to be pretty durable. (I've got a bottle but haven't used it much yet...) Cheers John

Author:	johnparchem [ Mon Sep 27, 2010 10:49 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
I worked for hours following Milburns method of cleared pumice with just alcohol, and hardly filed anything. I switched to using shellac and a pumice bag, and filled the back and sides and neck in an afternoon, following the technique that Ronald Louis Fernandez has in a DVD. It violated each and every rule that the milburn guide had on using pumice (including using those silly pumice bags). The fill looked great.

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Author:	rono [ Mon Sep 27, 2010 10:55 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
johnparchem wrote: The fill looked great. That looks fantastic!

Author:	WaddyThomson [ Mon Sep 27, 2010 10:56 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Yeah, I agree that some shellac is needed to get the pores to fill well. I always thought Milburn used a prepared muneca, but did not add shellac while pumicing. Is that a word?

Author:	johnparchem [ Mon Sep 27, 2010 11:35 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
WaddyThomson wrote: Yeah, I agree that some shellac is needed to get the pores to fill well. I always thought Milburn used a prepared muneca, but did not add shellac while pumicing. Is that a word? They may have used old muneca with shellac but you would not know it from their guide: "We will not be using any new shellac during the entire pumicing process. This is very important- additional shellac during the pore-filling process will inhibit the operation. We will be using the already dry shellac "spit coats" that we have previously applied to the guitar. All that is used is the muneca loaded with alcohol and a very small amount of pumice applied to the muneca surface." On the flip side I followed the rest of their guide to finish the french polish and had good results. I went back to the guide often when ever I had problems.

Author:	WaddyThomson [ Tue Sep 28, 2010 8:38 am ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
I think the key is "new shellac". That means there is shellac in the muneca, i.e., a prepared muneca, which has dried shellac in it.

Author:	Nate Swanger [ Tue Sep 28, 2010 6:30 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Well i sanded it all back down, pretty sure its that the pores got filled and i used too much denatured and it got down past the pumice and removed the color some how from the tubes. I cant really get it all out but its a bit better after sanding and re-shellacking. with any luck i can pore fill a bit more gently and not make it worse. if any one still knows any tricks let me know!

Author:	Nate Swanger [ Thu Sep 30, 2010 12:28 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Actually, after some indepth reading/searching I think its a combination of uncleared pumice getting down into the pores and also my 3 coats of 2# may have been too much and preventing wood fibers from being scratched up by the pumice. I sanded back and did the whole back a second time and had the same problems so im going to try it your way Waddy, If you get a chance could you post a picture of your pounce you use to tap against your muncea. Plan is to try and get the pores open again by sanding down. Then put 1 coat of 2# on the back FP style with a muncea. Then use that core to start pore filling with pumice. Hopefully i'll get a bit better slurry doing it your way, especially now that i have a better understanding of whats going on/wrong.

Author:	WaddyThomson [ Thu Sep 30, 2010 2:09 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
I just took a piece of T-Shirt material about 5" square, and put a couple of tablespoons of pumice in the center, pulled up the corners and tied it with a string. It looks like a muneca when you are done, except the center is a lump of pumice. It distributes a fine powdering of pumice on the muneca, instead of a clod, like you get when you dip the muneca in pumice on a paper. I never liked that method of getting it on the muneca. Then I remembered that Ron Fernandez uses a pounce, but the difference is that he puts the pumice directly on the instrument, which I don't like to do. Any way, I tried it, and it worked great.

Author:	Nate Swanger [ Thu Sep 30, 2010 2:59 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Thanks, I'll give it a try. Any thoughts Waddy on whats causing the white spots? (have you seen them at all on any of your EI rosewood?)

Author:	runamuck [ Thu Sep 30, 2010 8:13 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Nate Swanger wrote: Thanks, I'll give it a try. Any thoughts Waddy on whats causing the white spots? (have you seen them at all on any of your EI rosewood?) How humid has it been while you've been applying the polish? Moisture trapped in between thick layers can look exactly like that.

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Author:	Nate Swanger [ Thu Sep 30, 2010 8:21 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
runamuck wrote: Nate Swanger wrote: Thanks, I'll give it a try. Any thoughts Waddy on whats causing the white spots? (have you seen them at all on any of your EI rosewood?) How humid has it been while you've been applying the polish? Moisture trapped in between thick layers can look exactly like that. I dehumidify to 45% it always stays with in 40-50% Rh by count of two different electronic hydrometers. I'm not really polishing it yet though, this is just a pore fill with some 2# shellac coats rubbed on prior. I actually spent the last 2 hours sanding it all off and trying to clean the pores but they still have a whitish tint to them, not sure if there is still gunk in them or what, i've been using some denatured between sanding to help try and delude some sanding dust down into them and what ever shellac is stuck in the pores, might help, i dont know, I'm honestly out of options so after i finish sanding i will probably just fill it the way Waddy does and move on, call it a learning experience and try z-poxy or drywall with dye on the next one. Honestly all the you tubes i've seen make it look so effortless, i'm having a hard time raping my head around what im doing wrong.

Author:	JohnAbercrombie [ Thu Sep 30, 2010 9:02 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
Nate- What grade (grit) of pumice are you using? Can you hear the wood 'grinding' as you work? I learned a bit about FP when I took a class at Sergei de Jonges. We used a 50:50 mix of two grades of pumice with a bit of dry artist color mixed in, with just a sealer coat of shellac before using pumice. Picked up the pumice on the (very small) pad and wet with alcohol. Getting a few pieces of 'orphan'/opportunity IRW from Allied for practice, or just filling/finishing a jointed back (or something else from the woodpile that has open pores) that hasn't been used yet, might be worth a try before giving up on the technique. I know (from experience) how frustrating it can be to have finishing problems after investing a lot of time in building an instrument. Sometimes stepping back for a few days can help. Cheers John

Author:	WaddyThomson [ Thu Sep 30, 2010 10:09 pm ]
Post subject:	Re: Possible Issue Pore Filling With Pumice
To tell you the truth, it does not matter how much shellac you have on the guitar. I have pore filled after nearly completing the FP finish. Pumice and shellac fill the pores as well as pumice, wood and shellac. It is a little slower, but it works just fine. I have found that rubbing hard does not help. I seem to have more muneca hangs when I rub too hard.