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I successfully repaired a crack in the waist of a side with CA, but now I am left with a dark line of CA. Is there anything that will dissolve the CA near the surface, and some technique that will hide the glue line?

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A higher purpose for wood.
Rich Smith
Issaquah, WA

Nothing I can think of, sorry!

Visiblity is one reason to use hide glue (hot) for crack repairs in non-dark woods (in a dark set of EIR, it doesn't much matter...)

Acetone will dissolve CA, but I would test on scrap and wait till others chime in, there may be better way.

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Billy Dean Thomas
Covina, CA

"Multi famam, conscientiam, pauci verentur."
(Many fear their reputation, few their conscience)

Hi
what is making it dark? is it dirt in the crack? the ca we use dries pretty clear.
sounds like one of those fun jobs where you get to scratch all your glue out of the repair you did, clean it out and re-do it!
have a gander at frank fords site frets.com for some help, he's the master!
good luck, i'd be interested to see photos if its easy enough to do?
cheers
p.s when regluing (if you go down that route) if the crack doesn't need to be covered with clamps, you can sand over the glue -filling the crack with correct colour dust. I understand you may not be able to do it here but i've had pretty good results with this method before (works great on r/w fingerboard chips)

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www.theguitarrepairworkshop.com

Unfortunately, my crack will be very visible.  I used clear CA so I don't know why its so dark.

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A higher purpose for wood.
Rich Smith
Issaquah, WA

[QUOTE=Mattia Valente]Nothing I can think of, sorry!



Visiblity is one reason to use hide glue (hot) for crack repairs in non-dark woods (in a dark set of EIR, it doesn't much matter...)[/QUOTE]
Do you mix dust with the glue?  Is hot hide glue the only glue that won't be darker than the wood?

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A higher purpose for wood.
Rich Smith
Issaquah, WA

It's possible that the crack was not fully closed and you're seeing the gap
which would appear dark, even if slight. If the crack were fully closed it
should not appear too dark after it was sanded unless it was a low viscosity
CA that really saturated in to the wood around it. If this were the case then
you are seeing darker wood there because it is essentially finished. Wipe
some naptha on the side to see what the finished color will be - it's quite
possible that the darkness will at least come close to matching the rest of
the wood when it is finished.

_________________
Eschew obfuscation, espouse elucidation.

I wiped paint thinner on it and the crack was darker.  So it seems if there were a way I could dig out the CA then I could fill it with something that would match?

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A higher purpose for wood.
Rich Smith
Issaquah, WA

That's a tough one, and unfortunately I think with out some seriously
delicate patchwork it's not going to go away.

I doubt very much that you're seeing any actual dark substance within
the crack, but rather the lack of substance. Even a small gap when filled
with something clear like CA will appear darker, simply by the light (or
rather lack thereof) refracted through the fill. If your sides are thin
enough I would bet that the crack would actually look lighter than the
finished wood with a decent powered light source behind it.

I hate to say it, but the easiest way by far to get rid of the crack is by
getting rid of the side. If you're building this instrument to sell, then I
would also say it is the cheapest way to fix it after figuring in the cost of
your time. It looks like a compression fracture, and unlike a break on the
outside of of a bend those will never go away.

I say scrap it and move on with a new set of sides. You'll be much
happier when the instrument is done.

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Eschew obfuscation, espouse elucidation.

Alas, I hate to admit that you are right, but you probably are.  I'll get new sides and move on.  Thanks David!

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A higher purpose for wood.
Rich Smith
Issaquah, WA

I guess I shouldn't have said "scrap it", but rather sunburst the burst the
back and sides. Shading is a beautiful thing, and is a wonderful age old tool
of hiding defects. If you don't want to burst this one then set it aside for a
future project.

_________________
Eschew obfuscation, espouse elucidation.

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Eschew obfuscation, espouse elucidation.

Ricardo

Beautifull Koa... worth trying to save I'd say.

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Joe Beaver
Maker of Sawdust

Joe, that was my thought.  Maybe I too will be a converter of big boards into smaller!

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

I cleaned out the dark stuff from the crack.  I have varying colors of koa dust.  Which glue should I use to mix it with?

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A higher purpose for wood.
Rich Smith
Issaquah, WA

Cyanoacrylates, such as Hot Stuff, require a special solvent for effective clean-up. With normal safety precautions, Super Solvent can be used to clean hands or to remove glue spots from clothes or working surfaces.
Do not use on lacquer, butyrate, or nitrate-based finishes.


I think it is actually acetone

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Greg
http://garibaldiinstruments.com/

[QUOTE=Hesh1956] Not to reopen any old wounds here on the OLF but
again I am one who is firmly in the "no CA ever touches my stinkin
guitars" (beyond inlaying some dots....) camp.[/QUOTE]

Uh-oh. Where's Rick T today?

I'm one to say that CA glue has it's places. No creep, decent gap filling
strength, bonds well to non-porous surfaces, heat reversible, low
flexibility, variety of useful viscosities, etc.

Still, as Hesh pointed out, it is quite likely to show through most finishes
in the future. If the area is saturated and hardened with CA then it will
move differently than the rest of the wood through cyclic humidity
changes, and generally will show in the crazing as the instrument ages.
There are a lot of lacquers like McFadden's however that seem to have a
very high plasticizer content and may age better than others.

Really though, I would burst it in a heartbeat. Why do you think bursts
became as popular with manufacturers as they did? A natural finish is
certainly easier to do in theory, but a burst allows for so much room
for error throughout the whole building process without any visible effect
on the finished product. It's a beautiful thing......

If the existence of the flaw (though it may have no real effect on the
finished product) bothers your conscience, mark it down a hundred
dollars and sell it as a second. Tell a customer about a flaw that they may
never otherwise know about and you'll be golden in their eyes.

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Eschew obfuscation, espouse elucidation.

Hesh, I wouldn't sell an instrument with a crack in it.  I'll get new sides and move on. Chock it up to learning, expensive as it was. Thanks all for the feedback - much appreciated!

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A higher purpose for wood.
Rich Smith
Issaquah, WA

I'll use CA wherever it's appropriate, especially when gluing stuff like carbon fiber to wood or for gluing frets in. Of course it's great for inlays.    

I thought David's first wordless entry here was just perfect. 'Burst it.

The more you try to hide that, the more visible it's going to get, and no amount of koa dust, pixie dust, or star dust is going to make that crack disappear under a clear finish. Put a strip of fabric or a spruce pillar behind it.

I've seen some very high dollar luthiers' work fixed and bursted around here... Yes, cross grain cracks in flame figured woods fixed with superglue. The work of probably three dozen luthiers comes through our spray booth here in a year's time, and everybody...and I mean everybody has trouble with koa or flamed maple from time to time.   Structurally it's probably stronger after it's fixed and backed up!

David BTW, beautiful sunburst job!!

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A higher purpose for wood.
Rich Smith
Issaquah, WA

[QUOTE=Ricardo] David BTW, beautiful sunburst job!![/QUOTE]

Thanks, I actually did that burst in one of my previous lives when I was
working back in Kalamazoo.

That was a shot of a 40's Gibson L-5, not mine.

If a crack is solidly repaired and bursted over, and would have no effect
on tone, aesthetics, structure, stability, anything tangible at all...... is
there a defect in the end product? While we're at it, if a tree falls in the
forest and there is no one around to hear it........

If a mistake can be well repaired with no signs or symptoms remaining,
then the existence of the mistake is more a question of philosophy. Punch
a big hole in the face of a headstock then made a beautiful inlay to cover
it, is it now a flawed unsalable product or is it a custom upgrade? In
replacing a fingerboard on a 50's D-18 I drilled a dot about .100" off in
one place. I removed the dot, patched it with a cutoff piece of the same
fingerboard, and redrilled. It is impossible (not virtually impossible,
but truly not possible) for anyone to see. Would you consider the board to
be perfect, or does the existence of the repair make it flawed? I say a flaw
does not exist unless it can be detected or has an effect. If it holds
neither of those properties than I would be challenged to figure out what
properties it does have to consider it a flaw.

I should say that although I can understand your ideals, I've been moved
in recent years to adopt a more pragmatic approach to instruments. Not
less caring or particular about relevant details, but being more "down to
earth" in deciding what I feel is relevant to an instrument's quality.

Granted, the one lingering complication in this particular case would be
it's effect on the crazing pattern in that one particular spot in the future.
Still this could probably be worked around with perhaps a sizing coat or a
shellac sealer with a little extra gum mastic, then flexible lacquer like
McFadden. Or it may be no problem at all.

As Rick can surely attest to better than myself, many have mythically high
assumptions of the perfection of instruments at the top. Great builders
aren't infallible, they just know how to deal well with mistakes that may
happen.

Not trying to push any buttons, just throwing out some conversation
starters for a visit to the coffee shop.

Burst it man.......

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Eschew obfuscation, espouse elucidation.

David, is not unusual to burst koa?

_________________
A higher purpose for wood.
Rich Smith
Issaquah, WA

I'm not David, but who cares if it's unusual. That makes it worth more.

Actually, we burst koa and it's drop dead beautiful. I'll do a kind of "tobacco 'burst" with just US Cellulose "Warm Brown" and "Van Dyke Brown" MEK stains straight on the wood. To go more opaque, you can shoot the stuff onto tacky sealer or mix it in with the finish of your choice. On that one I'd do the wood stained burst first, and then hit the sealer coat to go really dark in the waist, etc. It's kind of a hybrid 'bust techinque.

BTW, I should have at least one of my stained-in-th-wood burst jobs up at H'burg.   It's a very old timey look, kind of like late teens and Loar era Gibson stuff.