A hairline top crack? (Pics)

Construction and repair of Classical Guitar and related instruments
User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Thu Jan 25, 2018 11:36 am

Some more pics here: https://files.fm/u/zt2yfs5t

I think it's easier to see it in these pics (especially pic named "cr"). I would appreciate your thoughts.
Becoming a great musician is about becoming a great human being.

User avatar
Michael.N.
Posts: 7484
Joined: Sun Mar 25, 2007 7:28 am
Location: UK

Re: A hairline top crack? (Pics)

Post by Michael.N. » Thu Jan 25, 2018 11:54 am

That's not definitive. It does appear to cross a grain line but then it's quite possible that it's actually two cracks. A little like medical matters it's foolish to diagnose it through the internet, you really need to get it to a guitar doc.
Historicalguitars.

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Thu Jan 25, 2018 12:08 pm

Michael.N. wrote:
Thu Jan 25, 2018 11:54 am
That's not definitive. It does appear to cross a grain line but then it's quite possible that it's actually two cracks. A little like medical matters it's foolish to diagnose it through the internet, you really need to get it to a guitar doc.
You are right, thanks Michael!
Becoming a great musician is about becoming a great human being.

SteveL123
Posts: 1303
Joined: Thu Feb 09, 2017 5:05 pm

Re: A hairline top crack? (Pics)

Post by SteveL123 » Thu Jan 25, 2018 2:25 pm

Arash Ahmadi wrote:
Thu Jan 25, 2018 9:32 am
SteveL123 wrote:
Wed Jan 24, 2018 11:54 pm
Found this crack finding techniques:

"Put naphtha on the outside of the crack, all along the length. Then look inside with a mirror and flashlight. You'll see wet spruce."

Naphtha will evaporate and leave no trace.
Thanks Steve, it sounds a bit risky for this guitar. Does it work with all finishes?
I don't think it harms most guitar finishes but you should wait till a Luthier with experience with such procedure chimes in first. A readily available source of Naphtha is cigarette lighter fluid.

User avatar
Beowulf
Posts: 1194
Joined: Wed Aug 03, 2016 5:02 pm
Location: London, Ontario CANADA

Re: A hairline top crack? (Pics)

Post by Beowulf » Thu Jan 25, 2018 2:36 pm

One thought: if this was not present when you purchased the guitar and given that it extends on both sides of the bridge (reaching the lower bout and the rosette), I would suspect a hairline crack in the top.
1971 Yamaha GC-10 (Hideyuki Ezaki)
2017 Yamaha GC82S (Akio Naniki/Naohiro Kawashima)

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Thu Jan 25, 2018 8:26 pm

Beowulf wrote:
Thu Jan 25, 2018 2:36 pm
One thought: if this was not present when you purchased the guitar and given that it extends on both sides of the bridge (reaching the lower bout and the rosette), I would suspect a hairline crack in the top.
It's not on any sides but middle of guitar and it is visible (more in the latter) pics when zoomed in.
Becoming a great musician is about becoming a great human being.

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Thu Jan 25, 2018 8:28 pm

SteveL123 wrote:
Thu Jan 25, 2018 2:25 pm
Arash Ahmadi wrote:
Thu Jan 25, 2018 9:32 am
SteveL123 wrote:
Wed Jan 24, 2018 11:54 pm
Found this crack finding techniques:

"Put naphtha on the outside of the crack, all along the length. Then look inside with a mirror and flashlight. You'll see wet spruce."

Naphtha will evaporate and leave no trace.
Thanks Steve, it sounds a bit risky for this guitar. Does it work with all finishes?
I don't think it harms most guitar finishes but you should wait till a Luthier with experience with such procedure chimes in first. A readily available source of Naphtha is cigarette lighter fluid.
Sure, thanks!
Becoming a great musician is about becoming a great human being.

SteveL123
Posts: 1303
Joined: Thu Feb 09, 2017 5:05 pm

Re: A hairline top crack? (Pics)

Post by SteveL123 » Mon Jan 29, 2018 3:57 am

Arash Ahmadi wrote:
Thu Jan 25, 2018 9:32 am
SteveL123 wrote:
Wed Jan 24, 2018 11:54 pm
Found this crack finding techniques:

"Put naphtha on the outside of the crack, all along the length. Then look inside with a mirror and flashlight. You'll see wet spruce."

Naphtha will evaporate and leave no trace.
Thanks Steve, it sounds a bit risky for this guitar. Does it work with all finishes?
Per this viewtopic.php?f=11&t=117803 Naphtha is safe on French polish.

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Wed Jan 31, 2018 5:45 pm

Update: I've shown my guitar to a local luthier and he thinks it's a so called "mirror crack" and I should wait 4-5 months to see how it turns out. I will keep it in the room with the humidifier.

Based on the talk I had with him, I've concluded that it's too risky to repair anyway... it makes me wonder if there's any safe way to repair it without affecting the sound.
Becoming a great musician is about becoming a great human being.

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Wed Jan 31, 2018 5:46 pm

SteveL123 wrote:
Mon Jan 29, 2018 3:57 am
Arash Ahmadi wrote:
Thu Jan 25, 2018 9:32 am
SteveL123 wrote:
Wed Jan 24, 2018 11:54 pm
Found this crack finding techniques:

"Put naphtha on the outside of the crack, all along the length. Then look inside with a mirror and flashlight. You'll see wet spruce."

Naphtha will evaporate and leave no trace.
Thanks Steve, it sounds a bit risky for this guitar. Does it work with all finishes?
Per this viewtopic.php?f=11&t=117803 Naphtha is safe on French polish.
Thanks!
Becoming a great musician is about becoming a great human being.

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Wed Jan 31, 2018 5:47 pm

By the way, I wonder if anybody is familiar with the "mirror crack" here.
Becoming a great musician is about becoming a great human being.

oc chuck
Posts: 534
Joined: Sat Oct 03, 2009 5:43 pm
Location: orange county, ca.

Re: A hairline top crack? (Pics)

Post by oc chuck » Wed Jan 31, 2018 6:32 pm

This is a test I was shown by two luthiers.

Lay the guitar on a table so there is a light reflection across the crack area.
Gently press on one side of the crack, 1/2" away. If there is a break or refraction
in the reflection at the crack, it may be in the wood. If no break or refraction,
it may be a finish crack.

It may not be 100% accurate, but it is a good indicator.

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Wed Jan 31, 2018 6:53 pm

oc chuck wrote:
Wed Jan 31, 2018 6:32 pm
This is a test I was shown by two luthiers.

Lay the guitar on a table so there is a light reflection across the crack area.
Gently press on one side of the crack, 1/2" away. If there is a break or refraction
in the reflection at the crack, it may be in the wood. If no break or refraction,
it may be a finish crack.

It may not be 100% accurate, but it is a good indicator.
Thanks Chuck, I see but I am a bit too afraid to press it down as the top is very very thin. But I think I have a photo that is taken in the condition that you suggest. Here are the photos:
https://files.fm/u/ws5egafe
https://files.fm/u/j6eusa4g
https://files.fm/u/zt2yfs5t
Becoming a great musician is about becoming a great human being.

Nikos_Greek
Posts: 243
Joined: Thu Jun 22, 2017 9:18 am
Location: Vienna, Austria

Re: A hairline top crack? (Pics)

Post by Nikos_Greek » Wed Jan 31, 2018 7:26 pm

Hello Arash, have you contacted the luthier? I had a humidity problem with my guitar which thanks god is solved now and when I contacted my luthier he proposed to build another guitar for me straight away without me suggesting that. A serious luthier should be able to offer solutions to these problems although I understand the shipping would be a problem in your case.
Regards, Nikos

User avatar
Arash Ahmadi
Posts: 701
Joined: Thu Oct 05, 2017 7:38 pm

Re: A hairline top crack? (Pics)

Post by Arash Ahmadi » Wed Jan 31, 2018 7:41 pm

Nikos_Greek wrote:
Wed Jan 31, 2018 7:26 pm
Hello Arash, have you contacted the luthier? I had a humidity problem with my guitar which thanks god is solved now and when I contacted my luthier he proposed to build another guitar for me straight away without me suggesting that. A serious luthier should be able to offer solutions to these problems although I understand the shipping would be a problem in your case.
Regards, Nikos
Hi Nikos, building another guitar is certainly a great solution! I have contacted my luthier but he is not sure it's a crack.
Becoming a great musician is about becoming a great human being.

Return to “Luthiers”