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I today bend a side of mahogany (honduran), straight grained, but I have a slight crack or tear in the outside of the upper bout.
What's the best fix?
If I sand, leaving dust in the crack, and apply superglue, will the glue enter the grain and wick a bit, showing as a darkening of the side at that point?

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

I like HHG for this job, and fix it before you glue the sides to the end blocks, so you can clamp the crack closed if you need.

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https://www.facebook.com/profile.php?id=100008907949110

Can you post a picture? Which way is the crack running?

I don't think there is a need for any sanding or dust, if I'm understanding the type of break you are referring to. I would make 2 shaped cauls (only if necessary) for both the inside and outside of the rib. Run HHG into it and allow it to dry. Repeat with more glue and then clamp.

No pic at the moment, crack/tear is straight across the width of the side, middle/outside of upper bout.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

If the crack is cross grain you'll never be able to hide it.

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

I've not had full cracks across the grain, but I've had figured wood "fold", with a noticeable crease, across the grain. As Laurent said, I've never been able to hide these "invisibly". There always remains a dark shadow of the crease. With long grain cracks, you can generally hide the crack repair in the grain of the wood.

If this is an early guitar for you, a possible fix is to glue a piece of the side cut-offs on the inside of the cracked side to support it, then sand the outside of the side off to minimize the crack appearance. The best solution is to get another side.

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Gene

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

Colin I agree with the above, you'll never hide a cross grain crack. You will need a matching pair to replace it unless you are lucky enough to find an orphan side to match.

Been there and dunnit,

Bill

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Dream to be a luthier

Cross grain cracks are the most difficult to repair as stated above but you can make the more unnoticeable . Stain the set and when you start the finish , shoot some satin over the cracked area , this helps to diffuse the light and cloud the area of the crack , then finish up with you finish. While it won't make it disappear , it can make it hard to detect.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

It happened to me on my latest guitar, Indian rw. There was a knot shadow on the interior. I avoided the area and well went fine, but the mold fit was a bit off so a couple days later I decided to touch it up. Against all care an precautions, it of course snapped open, about 0.06 deep across the entire width. I worked in fish glue, let it soak in for a couple minutes then clamped it very tight between two soft spruce cauls. It is absolutely invisible. Of course the chances of success decrease dramatically with light colored woods and/or creases.

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Build log

Thanks very much for all the feedback, but the other side cracked in exactly the same area, but quite a bit worse, so I have scrapped them.
There is a fair bit of runout in the area, about 1 in 5 slope (2 mm side, 10 mm long split slope across thickness)
I have extra sets of sides - this is old, recycled honduran and was lucky enough to get 4 sets out of what was given to me.
Maybe I am flogging a dead horse, but if I can bend these, I can bend almost anything!
I think there is something wrong with my technique (new blanket and spring steel slats instead of bulbs and aluminium) and I think it may be getting the sides in good contact with the heat source) despite using clips on the slats.
They may in fact be part of the problem, holding the slats too tightly causing the stack to separate as it is bent.
I went back to John Hall's tute on bending, and will try his way (lower bout/upper bout then waist) after I make up "rollers" like he uses with his benders.
Swift note about John's service - the router speed controller packed up on me after first time it was used, and he very quickly replied saying another one was on its way, international.
Big Thanks John!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.