MIMF

Hello- I'm on the downhill side of my first acoustic build and have ran into sort of a snag. I'm trying to fill a few very small gaps between the edges of a redwood soundboard and maple binding (see pic). I've tried the superglue/sawdust technique on a piece of scrap, but the mixture doesn't seem to dry (maybe because the sawdust is too oily?). From there I tried titebond and 5 minute epoxy, but both had the same problem. I have already filled some gaps on the back, and it seemed to work fine with rosewood, so I'm kind of stumped. I don't have a lot of interest in buying a bunch of burn-in sticks and trying to match a color, but that may be my only option. Any advice would be greatly appreciated. Thanks!

PS: I posted a pic for reference; sorry it's not the best perspective, but it's the only one I have right now.

Have you tried spraying or painting superglue accelerator to the gap just before stuffing the glue-dust mix into it?

Another approach is to make a redwood sliver, coat it in Titebond and wedge it into the gap, then sand or scrape it down afterwards.

And then, sometimes, I paint the gap with Titebond and then sand the top a little, letting the sawdust fall into/accumulate in the crack until it is pretty well packed in.

OR, rout out the bindings and start them again. Probably need to make slightly wider purflings to accommodate the places where there were gaps unless the bindings were scraped thinner there.

They will not fix themselves, it is YOUR work that will show, and you want it to be the best you can do, so do your best and re-do them, but this time make them conform to your design. Or just sunburst the guitar, that can cover up a few sins.

HOW TO TOUCH UP GAPS: DON'T LEAVE ANY. I know this may not sound sympathetic to your plight but it IS the way to fix the issue.

Soundboard woods are all very difficult to repair invisibly. Redwood is going to turn very dark if you make a slurry, or even if you get CA into the end-grain.
On the other hand, and as you already found out, dark hardwoods like rosewood & ebony are extremely forgiving to repair.

And Mr. Lewis is absolutely right. If you want it to look right you will need to do it again. It's either that or live with it.

I wouldn't get super glue anywhere near redwood! It will wick through the end grain and discolor the wood badly.

Do you know the heat gun trick? If you bind with Titebond or similar, you can warm up the area around the gap to the point that the glue softens and close the gap. When the glue cools, it regains virtually all of its original strength. Much better to correct the problem then to fill. This won't work if you bridge an inside curve (wood doesn't stretch), but for most problem areas, it's great.

Hi Alan,
If you use the finish material (lacquer?) as the binder for the (finely ground) sawdust the color match with the finished top should be close. If it is a few inconspicuous gaps this may look fine. It's nice to fit bindings perfectly, but it doesn't always happen. And as always , test on scrap first to see if it is close enough to call it good.

Hello everyone - First, let me say thank you all for the replies, they were all very helpful. I ended up taking Rick's advice and using a heat gun to pull the trim back in to get rid of the gap. The gaps were very slight, so this method worked fantastically.

As for the super glue problem: apparently gorilla glue is not the best type to use for this application. I had some gaps to fill from the fretting process on the side of the fretboard, but when I made an ebony/glue slurry it too would not dry. I finally bought some different glue and it dried in <10s (however this still wouldn't work for redwood as it dyes to glue too dark).

In any case, I've put the first 3 coats of finish on the guitar today, and things are going great. Thanks again!

As for the super glue problem: apparently gorilla glue is not the best type to use for this application. I had some gaps to fill from the fretting process on the side of the fretboard, but when I made an ebony/glue slurry it too would not dry. I finally bought some different glue and it dried in <10s (however this still wouldn't work for redwood as it dyes to glue too dark).

Sorry, I didn't follow that.
What did you use Gorilla glue for?
And what is the glue that dried in 10s?

Just for reference polyurethane glue (Gorilla) is the worst gap filling glue on the planet - it will just foam

When we say "Gorilla Glue" most of the time we are talking about the Polyurethane glue that Chuck has mentioned. I think they sell a CA glue too, and that might be what you are talking about...but please clarify.

Chuck Tweedy wrote:

As for the super glue problem: apparently gorilla glue is not the best type to use for this application. I had some gaps to fill from the fretting process on the side of the fretboard, but when I made an ebony/glue slurry it too would not dry. I finally bought some different glue and it dried in <10s (however this still wouldn't work for redwood as it dyes to glue too dark).

Sorry, I didn't follow that.
What did you use Gorilla glue for?
And what is the glue that dried in 10s?

Just for reference polyurethane glue (Gorilla) is the worst gap filling glue on the planet - it will just foam

No problem at all, I didn't specify. I was trying to use the gorilla glue as a sawdust/glue slurry to touch up some gaps. It worked great with rosewood, but on ebony and redwood it took almost 30min to dry, and even then it didn't dry solid (it could be pulled right back out of the gap). I switched to a cyanoacrylate glue which worked much better:

http://www.walmart.com/ip/24972951?wmls ... 16&veh=sem

Probably already mentioned but since superglue darkens sawdust mixture in a crack, I often mix "just the right" amount of baking soda with the wood dust to lighten it and the baking soda accelerates superglue very well.

No matter how you patch it you will end up with a patch, and that will show. Whatever happened to the desire to excel in skill, design, workmanship? If you want to do great work then DO great work. Make it happen. Filling gaps is settling for less than a good result.

On a "first" instrument perfection is sometimes hard to achieve, and "getting done" is half the battle. Fixing mistakes and small flaws to make an inconspicuous repair is a worthy skill to learn. We often share our methods and techniques to do this (and our failures), but usually recommend the person test it on scrap to see if it will satisfy their needs. Ultimately we must all decide what is "good enough" at any given time, for as we become more skilled, that will change.

Clay Schaeffer - MIMF House Philosopher

Yea verily!

Clay, of course you put the situation into perspective that I often forget.