Pore Filling

[Bob Webster]

Surely someone else has torn their hair out over this (see picture). How about weighing in with your favorite method, its merits and frustrations? Surely we can get a food fight going that will make us forget about French polish, etc.

[Mark Dobbins]

what picture?

[Bob Webster]

Of me, holding the stinking guitar body, above. You don't think I paid for that avatar, do you?

Cheers,
Bob

[Mark Dobbins]

Well Bob i use a rubber sqeegie , seal it first then fill , let sit overnight, sand with 220 then fill again, seems to work for me. Mark

[Bob Webster]

Ah, but what did you seal it with, fill it with, and what is the eventual finish?

Bob

[Mark Dobbins]

I use bulls eye sealcoat universal wood sealer, 100% wax free it works under all clear finishes, then if im spraying nitro i fill with behlen pore-o-pac grain filler, if im using ktm9 i use behlen waterbase grainfiller Mark

[Matt Hayden]

I've tried a bunch of different things, and I now use FFF pumice and fresh shellac. It takes a bit and requires care to not use too much pumice or too much finish or both, but with care it fills very nicely. The first couple of bodying sessions after filling require some care and sometimes re-filling, but it works out with patience.

[Bob Webster]

Matt, do you really get a dead flat, no pores showing kind of fill that doesn't show any shrink back after 6 months or so? I've seen some of Greg Byers' work using pumice and all of the pores are still evident. Nothing you could stand a toothpick up in, but still....

When I started FPing, I tried pumice. I've got a tremendous amount of patience for nipicky detail work but this method left me whipped. By the way, it's your fault we've come back around to FP.

After giving that up and getting subpar results with the usual suspects like the McFadden solvent- and water based fillers, I ended up getting much better results with epoxies and thick cyanoacrylate. There are some tricks to using the last two but overall, I can get to an absolutely dead flat surface with both. Unfortunately, whether I fill onto bare wood or shellac sealed wood, there still is some tiny amount of shrink back after 6 months. CA is now my choice just because of working times.

So, still, I'd love to know how you get the job done with pumice. I always ended up with little piles and swirls of the stuff hardened on the surface. Do you sand to level again before proceeding with FP?

Cheers,
Bob

[Matt Hayden]

It's not perfectly dead flat. But it's pretty good. On a guitar back I can get it really close.

Sorry to have pulled the discussion back to FP ;-)

I've tried epoxy and cyanoacrylate and they work. But I like doing it the old way. I'm not a professional builder - I do it for fun, and the process of getting a really nice finish is enjoyable. If I had to do it as a business, I'd probably do what you've done - you're catering to a market segment that wants that perfect flatness, etc.

I do the entire back, in a couple of sessions over a couple of days (usually after work I'll get in some time). When it's done, it gets a fine sanding, just enough to knock down any pumice grains on the surface. I do not use oil when pumicing, and I don't use much pumice at all, not enough to pile up. I also wipe across the grain with a relatively dry rag when I'm done with a session (or rather a few minutes later, when it's had some time to dry) just like burlap filler, and it seems to help without pulling all the stuff out of the pores.

It's not perfect but it works, and it's a good mental exercise. Lots of light, not a lot of shellac, not a lot of pumice, grind it carefully, and it eventually looks good, if not 100% pore-free.

[Bob Webster]

I think my obsessiveness with perfect pore filling has to do with trying to make the transition from fun to commercial competitiveness. As a developing luthier in the marketplace, one has to try to fight one's way up through the tiers in quality that represent the competition. With luck and help, workmanship, aestheitcs, playability, and tonal properties of the product have to improve in concert with each other. However, some of the first tiers like the small to medium Spanish shop guitars are real barriers if the finish work isn't really up to snuff. They're damn nice looking guitars made by people who know what they're doing.

Interestingly, once all else comes together, finish quality ceases to be such an important issue compared to tonal quality and playability in the guitars of upper tier buillders. Customers become more philosophical about stuff like pore filling if their guitar sounds as good as a Ruck or an Elliot or whomever. Maybe that's a topic for a separate thread.

Cheers,
Bob

[stevenrosburg]

Bob,

I'm new to the forum, but not new to guitars. For what it's worth, I actually think a little bit of pores showing is okay if the finish itself is immaculate and the underlying wood is beautiful. I think if you get "too" perfect it starts to look artificial... probably because it is.

-Steve

[Russell Vance]

Bob, firstly, I use a commercial spirit based grain filler - thinned down with turps or white spirit/naptha and do a couple of applications over a 48 hour period (at least - it take a while for this stuff to gas off). I use a flat straight edge to wipe of the excess - although a terry cloth works pretty good across the grain). You must sand it flat if you don't wish to have to apply a lot of sanding sealer to cover and you must blow out all the residual sanding dust (and I mean compressed air here - a tack cloth won't get down in the micro pores) otherwize the lacquer will have difficulty pulling flat and smooth and will react with the dust/air pockets anyway.

Professionally, I am starting to do finishes without grain filling as discerning clients begin to appreciate the benefits of wood looking like wood and not your grandmothers coffee table as well as the sonic benefits of not having an additional layer of junk on the bits that matter. Rusty.

[Penql]

My favorite method, sadly, is unlikely to be a solution for you.

My favorite method:
Use non-porous woods when you want shiny.
Keep the finish thin and easy to repair.

If you must fill, finish and buff, use old fashioned paste filler, plenty of nitro and wait a month before you rub it out (gently).

Kudos to you for trying to get a fight going :)