Top center seam separation/split

[Andrew Wright]

Hi guys, I picked up a cheap nylon string Cort CEC5 which has a split running from the bridge to the binding. Just wanted to ask some advice on the best way to go about repairing or should I just leave it as is? as the guitar plays fine.

[Mark McLean]

Andrew

That doesn't look like a split in the centre seam of the soundboard, as it is not in the midline (or close to it).  It looks like a crack along the grain.  I am assuming it is not just in the finish.  I looks like it is right through the spruce soundboard?  If so, you need to consider what caused it? 

1. Is the guitar dry (action low, fret ends slightly protruding, soundboard flat or sunken)?  If so - or if you are uncertain - the first thing to do is to try rehumidifying it, e.g. by using the "Hesh technique" of hanging it for a few days with the body enveloped in a large plastic garbage bag that also contains some wet sponges or rags (the wet stuff is not in contact with the guitar, but it humidifies the air in the bag, and hence the wood).  This might close the crack - but you will still want to glue it, and probably cleat it. 

2. Has the guitar suffered a blow to the face, causing the crack.  If you bought it like this you probably don't know the history - but if there is a possibility of this scenario you need to check whether braces have been loosened, whether the bridge is tight, and whether the bridge plate (if there is one) is OK.   If everything else is OK, you will still want to glue and cleat that crack.  Left alone it will get worse, get dirt into it and become harder to close or fix later. 

But it looks fixable, and could leave you with a nice instrument. 

If you are up for doing it yourself, have a look at this pictorial on the Frets.com site, and try Googling for a few other forums and blogs describing similar crack repairs.  But make sure the guitar is humidified before you do anything. 

http://www.frets.com/FretsPages/Luthier/Technique/Guitar/Structural...

Good luck with it!

Mark

[Paul Verticchio]

Hi Andrew.

That is a really nice nylon string 'crossover' instrument. 

Mark gave you excellent advice. You can take it to the bank :)

I'd only like to point out that the guitar has a solid Cedar top, not spruce. The repair is the same for both woods. Cedar may re-humidify quicker than spruce. That's a GOOD thing.

Follow Mark's suggestions and you'll be back in business in no time.

Best of luck with the repair,

P :)

[Bob Steinarsson]

I have a 16 years old Larrivee that I bought cheaply that has got a crack like this. The crack is open, and it needs to be humified to close before gluing. It now lies in its case with a humid towel in an open plastic bag inside the body. The humidity inside is just below 70 degrees, and I plan to keep it there till the crack has closed. It has laid like this since Saturday evening, but not much has happened. How long time will the crack need to close? It is actually very narrow.

[Andrew]

It can be pretty variable, if in fact the crack will close with humidification. You should have a look inside under the crack and make sure there are no partially glued braces that could be holding the crack open.

[Andrew Wright]

Thanks Mark for the excellent detailed advice..much appreciated

[Howard Klepper]

I don't see a good reason to overhumidify a guitar by putting it in a saturated atmosphere before gluing a crack.  If the guitar cracked in a very dry environment, like 20% humidity, then a medium or high medium room humidity (like 60%) will close the crack, and after gluing all you need is not to let it get in that 20% environment again.

But if the guitar cracked at a good humidity--say in the 40's (perhaps it was built in high humidity)--and you need to raise the humidity up into the 90's to get the crack to close, what do you think is going to happen when the guitar is back in the 40's again?   If the guitar is not going to live in the tropics, then a crack which doesn't close with a little patience at 55-60% humidity needs splinting.

The crack in question here looks tight.  I would keep it at a middle humidity for a week, and if it stays tight, glue it.  I would not put it in a saturated atmosphere in a plastic bag.

And I agree that this crack might be from a trauma.  All the more reason not to overhumidify.