Strange marks in the neck

Timbuck · Jun 26, 2011

While doing restoration work on this old Martin "O"..I've noticed these strange thin black lines under the finish that run transverse from the ends of each fret ..at the heel they run into a distinct pattern..anybody got an idea what they are?

Doc_J · Jun 26, 2011

Looks like a cracked finish with possibly oil/dirt/grime in the cracks. That is a tough one to 'fix'. Stress induced from the frets it seems.
An interesting look.

I've seen something like that on uke that was shipped in -20F weather.

Timbuck · Jun 26, 2011

Yes thats the same sort of thing...very interesting..of course I'll leave as is..it adds to it's charm

Rick Turner · Jun 26, 2011

Why is it that such damage is desirable on vintage instruments and makes a new one unsalable?

And those lines are not under the finish; they're in it. Nitro lacquer. Notorious for such...

Moore Bettah Ukuleles · Jun 26, 2011

They are pencil marks to show the fret locations. I do the same on my ukes.

David Newton · Jun 26, 2011

Why is it that such damage is desirable on vintage instruments and makes a new one unsalable?

I don't know Rick, I'm starting to leave saw marks on my back wood, the vintage buffs are flocking to it.

Doug · Jun 26, 2011

Isn't it kind of odd that the stress marks line up with the fret slots?

Pete Howlett · Jun 26, 2011

Good you have one for your baseline now Ken... it's always good to have a precise reference point. Those are stress cracks in the finish. Adds charm on an old uke but is a nightmare when it happens to your new ones like the 6 I shipped before Christmas!

My current lacquer is amazing - flows out beautifully so I can get it ultra thin. It cures very hard. You can polish it out in 2 days - remarkable. When I find out the make I'll let you know. My friend here in the UK imports it from the US... very expensive but unlike anything I have used so far.

Doc_J · Jun 26, 2011

Doug said:
Isn't it kind of odd that the stress marks line up with the fret slots?

Different materials have different rates of thermal expansion. The frets do not 'shrink' as much in the cold as wood does, so that is the high point of stress in the finish and sometimes results in a crack.

Timbuck · Jun 26, 2011

Doug said:
Isn't it kind of odd that the stress marks line up with the fret slots?

Not when you think about it!....Over the years with temperature changes and humidity rising and falling..the neck stretches and contracts...bows and flexes due to the fretboard being different material to the neck (like the Bi-metal strip in industrial Thermometers) plus the brittle laquer overcoat the stress points are the fret saw cuts where the cracks in the laquer propagate from...the reason they are dark/black , I imagine, is due to lemon oil and sweat and muck leaking under the frets and out at the ends into the cracks over the years

ld:

Timbuck · Jun 26, 2011

Doc_J said:
Different materials have different rates of thermal expansion. The frets do not 'shrink' as much in the cold as wood does, so that is the high point of stress in the finish and sometimes results in a crack.

Like wot he says!

erich@muttcrew.net · Jun 30, 2011

Moore Bettah Ukuleles said:
They are pencil marks to show the fret locations. I do the same on my ukes.

Yeah, so you can hold your uke with your arms stretched up in the air and still know where to finger the frets :rock:

Strange marks in the neck

Timbuck

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