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I have several spots of yellow discoloration on a guitar top under a finish. This was an experimental project, so I'm not too worked up about it, but I wanted to see if others had an idea of what it is.
It appears to be in places that I would have used yellow glue or CA.
The finish is a 2 part catalyzed polyurethane product. It was applied about 18 months ago and only started to yellow in the last 6 months. Very spotty. Looks very bad.
What typically yellows under finish?
Are some finishes better than others to prevent this?
Is it direct contact with glue that causes it and will a sealer help prevent it?
I've never had issues with KTM-9 or French polish.
Thanks.
-j.

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“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy

I've seen CA do that over time where it wicks into the grain of top wood around a rosette or binding. Never seen anything else do it. I doubt the finish has anything to do with it or could prevent it.

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http://www.chassonguitars.com

J.,
It is the CA you used. There are certain brands that do this more than others. But I don't know which brands are the culprit. I've seen some guitars that Edward did that did the same thing around the rosette and he was using Lacquer. So I don't think it is the finish, but rather the aging of the CA under the finish. Just my .02.

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Tracy
http://www.luthiersuppliers.com

Well, I sure would like to know what CA brand does NOT do this...'cuz it is FUGLY.
I wish I could remember what brand of CA I was using...
I'm glad that its not a reaction to the finish, though.
-j.

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“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy

I had this happen on my first scratch build and the CA brand was/is Bob Smith - a very well respected CA brand.

This is one of the reasons that I HATE CA........ Sorry for yelling...... And sorry this happened to you J.

I have had it happen using LMI and StewMacs CA as well.

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tim...
http://www.mcknightguitars.com

UGH! Anyone have any experience with starbond yellowing....or more importantly, NOT yellowing?
Thats exactly where it is, though...right around the rosette and the bindings where I used CA. I need to figure out how to avoid that happening.
What do you tell a client when that happens?
-j.

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“If God dwells inside us like some people say, I sure hope He likes enchiladas, because that's what He's getting”
-jack handy

How bout a free burst?

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tim...
http://www.mcknightguitars.com