Repairing Top Crack/Separation

[A.Wilder1]

Picked up a fairly cheap parlour guitar for playing at home, sounds great!

However it has a seam separation in the top from the bridge down to the tail. It has already been repaired with two cleats marked with the red ‘X’ below.

The two pieces are flush but I can feel it if I gently run my fingers over it. It doesn’t appear to have any glue along the crack.

Is it possible to improve upon this repair? Anything I can DIY or is it a complicated process and I should take it in to get looked at? Impossible to hide?

I’d appreciate any advice!

[ProfChris]

A high level restoration expert might be able to improve the look, at a cost several times the value of the guitar!

Filling the gap with anything but a spruce splint will make it look worse for sure. And fitting a splint is something most luthiers would decline to do here, I think, in case they made it look worse.

[A.Wilder1]

Thanks for your reply!

The guitar is a little dry.

I guess maybe the best course of action would be to humidify it and see if it closes more? If it does would adding an additional cleat in the middle be a good idea?

I guess it couldn’t hurt.

[A.Wilder1]

Here we go;

[redir]

Given that hygrometer is correct 60% is pushing it. You do not want to over humidify the crack to shut it. You want to see if it shuts at a good average humidity, which obviously depends on where you live but, most luthiers consider that to be from 40-50%.

You can shut and re-glue the crack when it is over humidified but I speak from experience to tell you it will open again.

If it doesn't shut at 45% - ish percent then you need to fill it with a splint or, as some renowned repairers of guitars do now, colored to taste epoxy.

[A.Wilder1]

Thanks for the feedback. It has improved slightly at 50-55% the last 48 hours. The hygrometer only hit 60% as of today.

I was planning to back it off before gluing and will take your advice as low as 45%-50%.

Do you think there’s any harm with at 60% right now. I won’t be able to get to it till tomorrow evening.

[renoslim]

If 60 % is a problem then my whole herd is living on borrowed time

Here in Florida it is OFTEN over that in the summer. I do notice some loss of tone then, but
have not seen any damage. I worry more about low humidity in the winter, then run a humidifier
in my main guitar room.

Lee

[redir]

Like I said 60% was pushing it, but in Florida.... Hmmmmm. Probably not pushing it too much. The thing is luthiers pick an average so that the guitar can live in Florida summer just as it can a Colorado winter.

[phavriluk]

Folks, I don't see any cause for concern, interest, or worry in those pictures. OP seems convinced that the top seam has separated. That's an opinion, not a fact, until a separation has been identified by normal diagnostic tests.

A prior and repaired separation will show a fingernail-catching seam, as the finish was broken and no refinishing was done. It is not evidence of a current separation.

OP suggested getting a professional inspection, which I think is a very good idea.

[A.Wilder1]

Got it down to 50% and the crack still looks fairly tight, to my eye the same as it was at 60%.



Any recommendations on glue for the top? Will one blend better on the crack? It still looks like a thin black line. Does it matter?

I’m currently looking at these two;

[Fathand]

Better choice

[redir]

It does look pretty tight. I would suggest gluing a cross grained spruce strip on the inside over the crack too. Much like you see on the center reinforcement on most guitar backs. You will have to fit it in with the braces. Thomson makes a great clamping jig for this but if clever enough you can make something yourself.


https://proluthiertools.com/wp-conte...007_1096-1.jpg

[Howard Klepper]

Before you glue it, you ought to check with thin feelers whether the diagonal brace(s) that run under that area are loose.

If not, work in Titebond Original with your fingers and glue a small, thin diamond cleat with its edges all tapered in thickness in the middle of the separation, with the cleat's long points on the crack. It can be a rub joint.

If the brace is loose, you are getting outside the DIY envelope.

[A.Wilder1]

Thanks for everyone’s advice!

I’ll check the braces next. If it’s good to go, I’ll get to it.

Is there any advantage on the recommended diamond cleat vs a strip?

Thank you.

[Howard Klepper]

A strip creates a stress riser along the grain lines. The diamond minimizes stress risers. And weighs less, although I don't think this is its main advantage.