Official Luthiers Forum!

I'm starting to look into finishing, and I'd like to practice on junkers before I try something on a nice guitar. I've got a Les Paul with a nice ding on the back of the neck. I assume old Harmonys and Silvertones and such have finish other than NC lacquer. So how does one go about practicing such repairs? As I sit here, I realize I could do a refinish on part or all of one of my old sacrificial lambs and then practice repairs on that. Any other suggestions? Also, just about everything I see addresses NC lacquer, whether it's repair or just finishing in general. Are there good resources for repairing other types of finishes? I'll admit I haven't done much research on this yet.

Thanks, guys.

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"Real guitars are for old people, Mr. Marsh."

Eric Cartman

An entire book could be written on this subject. First, I never assume what type of finish is on any instrument that is on my bench. I always do a quick acetone test to see if they are lacquer or a poly. For most guys without a complete finish operation that deals in modern poly coatings you are going to be limited to using CA as your final finish on most repairs. Dings and chips can be filled with med CA or a burn in stick and then sealed and finished with CA. You need to be mindful of finish repairs with CA on spruces. If the damage goes all the way to bare wood and you apply CA the spruce may very well turn green. A bit of shellac to seal the wood and then the CA in those cases but the shellac can cause a witness line if not done carefully.

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Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Thanks for the input. I'm not familiar with the acetone test. Could you tell me how that works? Also, I'm learning how to use CA for little fill repairs and such, but how large a repair can you finish with it? Probably depends on the skill level, huh?

I just got the burn-in kit from Stewmac, and I'm looking forward to learning how to use it. I've got a boatload to learn and that sounds good to me. Thanks again for your help.

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"Real guitars are for old people, Mr. Marsh."

Eric Cartman

To test finish composition with acetone pick an inconspicuous spot, I usually pull a tuner and test under its footprint. Take a Q-tip and wet it with acetone and give a quick touch and swirl on the finish. If it mars the finish it is a lacquer (or possibly a french polish or natural oil/varnish if handmade) if not it is some type of poly. Be careful not to get the Q-tip too wet or the acetone may run and spoil a fair amount of finish if it is lacquer.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

Thanks Brian.

The whole post is just a great tip. Don't ask me how I know, but this part is a warning that can save a ton of work hiding the errors that may be caused by not controlling the acetone.