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My second build is starting to come together, and I'm trying to apply lessons from #1 to #2. Pore filling was lets say, a "teachable moment", and this walnut looks like its really full of them. I have the StewMac water based filler, but was considering a z-poxy fill instead. Also, is there any harm is filling and sanding before I install the binding. Plan on using figured maple and haven't really considered where it falls in the filling process. Any tips of pitfalls to avoid would be appreciated!

Zpoxy is as good as anything, and probably better than the stewmac stuff you have.

There is no point in filling before binding. Get the woodwork done and then pore fill.

I think you'll like the Zpoxy fill. It really pops the figure of the walnut. You may
need two (or more) applications to get the pores filled, sanding in between. I
usually pad on a coat of thinned Zpoxy after the last sanding, to give me a level,
consistent surface with no sand-through spots. I agree with meddlingfool, there
is no purpose in filling before binding. The Zpoxy won't pull any stain out of the
walnut to discolor the maple bindings.

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

I've used the Stewmac filler several times with great results. Easy to use and easy to clean up. I spray two full wet coats of vinyl sealer before I fill, this protects any Maple binding or purflings. When I sand the filler, any white or light colored wood comes out clean. If you use a filler that is slightly darker than the wood, the grain will be accented nicely.

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It will probably be alright.

If you do use a pigmented filler, it is better if you seal the wood first. That will keep the filler from discoloring the wood.....which is especially important with maple binding....or with a light-colored wood backstrip.
.

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John

Thanks all. I had reasonable success (for first attempt) with the stewmac, but the zpoxy is really tempting. Saw some youtubes from individuals that were really convincing. No rush, so I'm doing a head-to-head comparison of the stewmac vs zpoxy on some scrap. I really appreciate the advice about how to deal with the binding. I was worried with the lighter colored wood, especially if using the brown filler. One last question, should I also hit the top (sitka spruce) with a thin layer of filler (clear zpoxy, if I do)? I know its not necessary, and may dampen the tone, but my first top looks like it could have used something to level it out more than the sanding and nitro. This would also allow me to more easily cover the binding without masking the top.

I've never done an epoxy pore fill, but I've used several other methods. Pore filling usually takes two or even three passes to get it just right, so you shouldn't be discouraged if you see some open pores after a first pass. Sometimes filler gets pulled out of pores or sanded through. You just have to be patient and meticulous. I like to tone walnut filler with warm colors and I usually use oil based filler and artist's oil colors for that purpose. As John said, it can stain bindings, too--always requiring some scraping. If you're good with a small artist's brush, you can paint a seal coat of shellac over back strips, etc., but that's a challenge, too. For a basic pore fill job that won't stain contrasting woods, it's probably hard to beat epoxy fillers.

Zpoxy isn't necessary or a particularly good idea for the top, unless the top is mahogany/walnut/koa etc.

IME both paste filler and Z-poxy look good on walnut. Walnut isn't as chatoyant as (IE) mahogany, and there isn't as much benefit in depth gained by using a clear filler.

Paste filler is faster and easier. I've used oil based and LMI's microbead filler on walnut. 6 of one, half dozen of the other. They look about the same when finished. Yeah, you'll need to mask light wood bindings, which is not necessary with Z-poxy.

Instead of masking the top, just seal it. In the past, I have sealed with thinned lacquer, but I am using dewaxed shellac more and more these days.
I know it is popular these days, but it seems to me that epoxy on a soundboard would be a bad idea.

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John

Thanks John. That's probably what I'll end up doing. If I were to fill the top with epoxy, I would likely sand it down close to the wood anyway, but I like the shellac sealing coat.

Is it a sign that you're hooked on lutherie, if you spend more time thinking about you NEXT guitar than the one you're working on now?

I've sealed spruce tops with epoxy and it works fine. No damping as far as I can tell.

Pore filling is about more than filling the pores. It's also about getting gaps between the sides and binding, and other voids elsewhere. Binding first for sure, then cleanup (sand out glue, level, scrape, etc) then pore fill, so that in addition to getting the pores, your get anything else that you dont even realize is there filled. I tried the Timbermate (I think..) from Stewmac and had poor results, compared to epoxy fills I've done. I never would, nor have I sealed the top with epoxy. I always do the top's final sanding and bevel the top after I pore fill.

I don't understand the idea behind filling the grain of a spruce top. Spruce is considered nonporous, and finishes very well with a few coats of lacquer. After buffing, the finish on my lacquered tops is about 1.5 mils thick.

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John

So, when sanding between zpoxy filler coats, I'm unclear on how much to sand. Seems you would not want to leave epoxy on wood, except in pores, right? So when sanding, any shiney spots are epoxy left on wood and need sanded? To get rid of the shiney spots, I'm quite certain I'm sanding down to wood. Are these shiney spots low areas that left epoxy unsanded? (I prep sanded to 320 before sealing and filling) When I wipe down with naptha, all the areas seem to blend nicely together, so I'm wondering If I'm ready to start applying nitro? I've read several books, and searched this forum, but didn't find what I was missing.

thanks

dave

The most common way of pore filling with epoxy is sand the first coat nearly to the bare wood, the second coat to level with no bare spots, and the third (if needed) the same. You either want no bare spots before applying the finish or you could sand it all the way to bare wood leaving it only in the pores, but In practice that is hard to do.

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Joe Beaver
Maker of Sawdust

For me it's because I hate finishing.

The shiny spots are unsanded epoxy (low spots). Joe Beaver's post is very important. Be sure you understand it fully. You need either a very thin layer over the entire surface or no epoxy except in the pores. If you wind up somewhere in the middle, you'll get splotches - DAMHIKT. But then again, only you will see them.

Kevin Looker

_________________
I'm not a luthier.
I'm just a guy who builds guitars in his basement.
It's better than playing golf.

Hey Kevin,
How's your V coming along?

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wah
Wah-wah-wah-wah
Wah

As has been already pointed out, you can go one of two ways: leave a thing coat of Zpoxy over everything, or sand the surface and leave filler only in the pores.

If you leave the epoxy only in the pores, I suggest starting with some shellac (my preference) or similar sealer before going to nitro coats. There will likely be some micro pores open after sanding the epoxy off the surface.

Thanks again. I did spray two thin coats of shellac after sanding. We'll see how it turns out.....worst case is I'll have a good campfire buddy, and a good learning experience.