Fixing Archtop Cracks

[Steve Bee]

I posted some photos of some cracks in the top of a Gibson L-4 on March 3, 2011.  Anyway, the cracks closed up but I am wondering what is the best way to fix/hide them?  There is also a small crack by the pickup switch.

[Pierre-Antoine Roiron]

First you have to glue the cracks if it's not already done, hide glue would be my choice here. Then glue some patches , then considering it's most likely a nitro finish, some finish touch-ups with clear nitro varnish and some sanding/buffing. They closed well, so you should have a good result.

Finish touch-ups are really hard to do if you don't know how, so think twice before you decide to make it yourself or not.

[Steve Bee]

I've been doing quite a bit of drop fills and touch up using both lacquer and ca glue with excellent success.  I will probably do as Dan Erlewine says and "court disaster" on this one.  I get confused when people say nitro lacquer or they say nitro varnish.  Are they the same or different?  And if different, what is the difference?  I live in a pretty remote area where there are not a lot of skilled repair people so I have been going it alone on just about everything....  Baptism by fire I have found is actually the better this way and it's the only option I have...

Thanks Pierre-Antone!!!!

[Greg Mirken]

My procedure is basically this: first the pickup hardware is removed to allow access to the inside of the body; hot thin hide glue is worked into the cracks while reaching in and flexing the top from underneath; light clamp pressure is applied to align the edges. Doesn't look like much touchup is called for.

Cleats are not necessary- these cracks happened because the instrument was abused and dried out. Cleats wouldn't prevent a re-occurrence, and it will be plenty strong if not mistreated.

[Steve Bee]

Thanks Greg...  Do you think that small separation line from the crack will go away?  Do I need to prep/sand/file the crack separation?  Or just glue it?  Thanks again.....  Steve

[Greg Mirken]

Do you think that small separation line from the crack will go away?

-no, but unless you're really good, your touchup will look worse.

Do I need to prep/sand/file the crack separation?

-no! (assuming no contaminants have been introduced to the crack)

[Steve Bee]

Thanks Greg...I'd really love to know what constitutes being good....I guess it would be the end result, right?   I am going to glue it and then tape off the sides of the cracks and brush a couple coats of clear lacquer and then sand and buff.  I know it's a little more involved than that, but does that sound right?  Or would you spray?  Crazy stuff...  Thanks again Greg....