Official Luthiers Forum!

I recall reading somewhere in the archives or another forum (i can't remember), that oil and saw dust can be used to create a slurry to fill the pores using True Oil & wood dust.

Is anyone out there familar with this method of pore filling, and If so, can you explain It in detail? Thanks.

Ron M.

No one has responded so I will. I haven't done this on a guitar, and I'e only done it once with True Oil, but I have done it lots of times on furniture with other oil finishes. I'll tell you how I do it in those circumstances, but you really must practice on some scraps of your guitar material before you attack your instrument.

Okay. I'd use 220-grit paper, and a generous flood of oil in whatever area I was sanding. I haven't used True Oil in a very long time, but I recall that it gets tacky pretty fast, so don't flood too big an area all at once. Oil a manageable area, and then start sanding with the grain. You will quickly raise a slurry of oil and dust, that will work its way down into the pores. Move onto another manageable area and repeat. Etc. Etc. When things start to get really tacky, rub the excess off the surface with a coarse cloth, wiping across the grain. 24 hours later, you will still have some excess on your surface, and it will be pretty hard, and you will need to sand it off with a finer grit--perhaps 320, 380, or 400. Don't over-sand. Get all the excess off the surface, and then stop. Chances are, you will have to repeat the process to get the pores fully filled. This time, you might try a slightly finer grit, and a little more effort. Repeat the wipe, off process. A day later, come back and sand off the excess.
When you can no longer see an open pore under strong, raking light, you are ready to start building surface coats of your oil finish. These you don't sand off. Be advised that they tend to soften the previous treatments of oil, unless it has hardened for several weeks.
Apply a little oil. Rub it and rub it. (I rub with my hand to build up some heat and flow it out). Go away for 24 hours. Then apply a little more oil, and rub like crazy. Repeat until you like the way it looks. You can often buff it to your satisfaction with a wool flannel cloth.
It generates just enough friction to soften the oil and flow it to a smooth polish. You can also buff with 0000 steel wool, and then with a flannel cloth. The steel wool will remove some of your built-up finish, though. Sometimes, that's a good thing.

Your guitar top does not need to have pores filled. It will be a closed pore wood. Just wipe some oil onto a small area, and then wipe off the excess a minute later, or even less time. Keep moving and wiping on and off. Do try to keep a "wet" edge between your work areas. By that, I mean to always work into an area that's still got wet or tacky oil on it. Otherwise, you might see witness lines between your work areas. When you've done the whole top, stop and go away for a few days. You don't want to impregnate the top with a lot of oil. On the top, you want a surface finish, so don't give it enough time to soak in. You might experiment with trying it over a wash coat of shellac, to keep it from soaking in. After you've gone over the top lightly and let it dry for a day or two, come back, sand or buff with 0000 steel wool, and repeat the process. Do this every few days until you like the sheen. Then stop.

I must STRESS that I just told you how to finish the top of a coffee table with an oil finish. I see no reason why the same method wouldn't work on a guitar, but experiment, experiment, EXPERIMENT, before you go at the instrument that took you so many weeks to build.

Good luck with it. I bet you'll like it. And, if not, you can sand it all off and spray or brush something instead!

I have done it on a couple of builds and works fine. I went ahead and did the whole finish with it. Cure time is long, but then again so is nitro. I still do slurry fills as much as anything, but the last couple qoing with z poxy. That said, will probably will do slurry fills again and soon.

I do something similar with egg white and 400 grit and some people who french polish use pumice and shellac to pore fill.

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Zac

Anchorage Alaska

Finshed my 1st! See #1 here

What advantage is this supposed to have over a traditional oil-based silex filler? Sounds like it would have more problems with shrinking and settling bacck.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

probably no advantage or disadvantage on the ones I have done anyway. I did the fill as just part of the wipe on tru oil finish/polish Still holding up to my knowledge but only 5 years out there.

For me and the egg method I use it because I live in an apartment and my wife will kick me outside if it smells and I like the NO toxic ingredients plus if I get hungry I can eat my pore filler

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Zac

Anchorage Alaska

Finshed my 1st! See #1 here

Howard, I'm not sure there is any advantage. I just want to try something that i can control the outcome of. I tried the Z-poxy and it did'nt turn out too good. I'm not blaming the product, but myself for not applying it correctly. i haven't settled on a filler yet, i'm just experimenting on scrap, Thanks.

Thanks cphanna for the detailed info.


Stan, did you fill the pores with the "slurry fills" basically the same way as cphanna?
Also, did you apply shellac before or after packing the pores with the slurry fill? Thanks

zac_in_ak i may experiment with the egg white as well before this is all over.

Thats funny
Zac, do you mix the egg white, or just seperate it from the yoke and slap it on?

Thanks
Ron M.

cphanna,
Thanks again for your comprehensive explanation. Do you use shellac at any point in the process?

Ron M.

I separate the white and use 400 grit sandpaper to rub it in. The sandpaper makes just enough sawdust to fill the pores and the egg white binds it in I do small sections in a circular motion. I did this on my first build, I overdid the back and sanded back a little and put another thin layer on and the mahogany was nice and smooth.

in the picture the back is done but the neck is not

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Zac

Anchorage Alaska

Finshed my 1st! See #1 here

Just filled with the slurry. Instead of sandpaper, use scotch brite pads. Once filled, sat for awhile as had other things to do. When got back to it, just started a fp type process until had it like I wanted and then sat for a month or more. buffed it out with one of those cheap 12" hand buffer things.

I did a mahogany neck like this 3 years ago and the filler hasn't shrunk yet, I used 320 wet-or-dry sandpaper. Advantage: the pore fills look a little more "natural" since they're filled with the the same material, it's not a clear filler, but not as opaque as, say, Pore-O-Pac walnut, or tinted a dark RW or black. Obviously it's more noticeable on lighter woods, not sure it would make a difference at all on a stained neck. Disadvantage: it requires much more effort and time.

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Laurent Brondel
West Paris, Maine - USA
http://www.laurentbrondel.com/

Regarding use of shellac, I didn't use it. But remember, I was describing the process for slurry-filling a walnut or mahogany table. I see no reason why you couldn't seal with shellac,
and if you planned to surface finish with something else (perhaps lacquer) then it would be a good idea. HOWEVER--AND THIS IS IMPORTANT-- be sure your slurry is fully dried and cured before you coat it with anything other than more oil. It's has been so long since I used True Oil, that you'd better check with the other guys regarding dry and cure time. It's an easy process, though. Good luck with it!

Howard, in fact, I prefer oil based pore filler so much that I used it on my recent archtop, which has a walnut and spruce body. I like the pore filler because I can color it with artists colors (oil based) to warm up the color of the wood. I've applied wiping oil finishes to furniture that was filled with silex and oil pore filler, and I like that combination, because I don't want a high gloss on my furniture, and because it is so easy to repair every year. Just a gentle buff with steel wool, another rub with oil, and a polish with flannel. Presto! I expect it would work about the same way on a guitar, but I haven't tried it.