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Hi everyboby:
I have a problem with the finish in a Martin acoustic neck. It is a nitro finish, a part is away, the customer removed other part, I can touch the wood. The remaining is soft and sticky.
My question is, start from scratch, remove old finish, sanding until the wood and apply a new nitro finish?.
Or could I clean up the old varnish and apply a new nitro finish on top?
Does anyone have experience with this matter?
Bets regards

Luis, I think you would be well served to either return the guitar to the customer with your best wishes, or tell the customer that you will refinish the neck in a proven manner of your choosing. I do not think that trying to finish the job the customer botched makes for a good job.

I think your problem is not with the guitar, it's with the mess the customer made of it. Resolving that won't be inexpensive.

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Peter Havriluk

Sticky lacquer cannot be repaired. It has to be removed. It is possible that only the top layer is damaged and you can clean it away and find sufficient hard lacquer underneath. However, it the gummy layer extends all the way down to the wood you have no choice but to take all the finish off and start from scratch.

Peter Havriluk, the customer allways is a mess, is the bisness

Barry Daniels, I'm afraid that we agree on the diagnosis. Thanks for your opinion.

Sticky lacquer on the neck is either heavy player grime build up or the lacquer has been ruined from a players sweat that is acidic, I have run into both.

Heavy player grime can be removed with first Naphtha followed by a good wiping with a diluted solution of Ammonia using a soft cloth. Lacquer is fairly resistant to being dissolved by Ammonia and whatever is left of it should remain after the crud is gone. It will readily remove a shellac or French polish finish though! Sounds like it is already too late for cleaning for your project as the finish has been mostly removed.

A players PH, if acidic, will readily soften lacquer and ruin the finish. This type of damage is NOT reversible and the neck needs to be taken back to the bare wood wherever the lacquer has been affected. If this is the case, do not re-finish the neck with lacquer unless it was not caused by the current owner. Your best off to get things sanded smooth and use a drying wood ( Watco, Walnut or the like) oil to finish the neck. Wet sand it with the wood oil to at least 600 grit.

If you are not sure about the cause, try cleaning first. I took in a Martin for work and was at first certain the neck was contaminated and the lacquer ruined from sweat, I told the owner the finish would have to be removed. The finish was soft and I could roll bits of stuff off in little balls. This usually indicates sweat ruined lacquer but I tried cleaning it first as described and was a bit surprised to find intact lacquer remaining below the removed gunk.

[quote="Resophonic"]Sticky lacquer on the neck is either heavy player grime build up or the lacquer has been ruined from a players sweat that is acidic, I have run into both.

Heavy player grime can be removed with first Naphtha followed by a good wiping with a diluted solution of Ammonia using a soft cloth. Lacquer is fairly resistant to being dissolved by Ammonia and whatever is left of it should remain after the crud is gone. It will readily remove a shellac or French polish finish though! Sounds like it is already too late for cleaning for your project as the finish has been mostly removed.......

Thanks for the answer. I think is the same problem. I will follow your comments. A question about oil finish. I am from Spain, now I only have Tru-oil from Birchwood Casey. Would be fine?

Tru-Oil is fine, follow instructions on the bottle.

Paul, you have tested Tru-Oil on top of lacquer?

I've found it works with lacquer or poly finishes. It's quite versatile.

_________________
"Act your age, not your shoe size" - Prince

Barry, I am assuming that from the description given, the Martin's lacquer finish is mostly gone. The drying oil is suggested to as a substitute for the missing lacquer, on bare wood. I always sand to blend the remaining lacquer where the neck meets the neck heel and head stock for a smooth transition. I have not tried Tru-Oil specifically for this use but not had any lacquer softening issues with the Watco I have used. When the oil is applied to the bare wood with some overlap onto the lacquer finish, it is left to sit for 15 minutes and then thoroughly wiped off. You want the surfaces to feel completely dry when done. It is absorbed by the bare wood but pretty much removed from the lacquer when it is wiped.

Don't worry everybody, I will check the oil finish (True-oil) method from Paul, and will send the forum my experience. If this doesn't work, I will sand and start from scratch applying a new nitro finish.
News ASAP. Thans for the help.

The TruOil feels great on the neck but it will not match the look of the nitro.

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Steve Smith
"Music is what feelings sound like"

But shellac would and I think has the best feel of any finish for a neck.

Hi, to close de post,
The neck finish was not nitro, after cleaning with nafta, a lot of a brown substance dissolves in the cotton pad. The finish was not clear (transparent), it had a brown layer inside. Could be some type of water finish, not poly.
So a lot of nude wood, sticky old finish, shaded... a mess, uff.
Repair the finish was not a option for me. Scrap and sandig until the wood, from back headstock to body joint. New nitro finish a littel shaded to macht the boby color and ready.
Best regards and thanks for your help.

Nice job

Sent from my SM-G970U using Tapatalk

_________________
Steve Smith
"Music is what feelings sound like"

Looking good now!

_________________
"Act your age, not your shoe size" - Prince