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Thread: Finish delaminating National RM-1

  1. #1
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    Question Finish delaminating National RM-1

    Took our ~10-15 yr old RM-1 out of the case for the first time in a few months and the top coat of the finish is peeling off about a third of the back (and a spot on the top edge of the peghead).... Had been through a couple of moves the past couple years, but no real extremes or sudden shocks of temp or moisture AFAIK. Why did it do that?

    Would it be practical to strip and refinish just the back, and if so, what's the best DIY option for doing that? I believe National refers to their finish as "polyester"... all I know so far is that the bits that flake off are not soluble in alcohol.

    Can the portion of the top coat which is still adhered be peeled off the base coat, and then what?-- French polish, water-base poly, spray lacquer, acrylic clear-coat...????

    Sand down to the bare walnut and refinish with Tru-Oil?

  2. #2
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    Default Re: Finish delaminating National RM-1

    I picture would help. I suspect you would have to sand of the remaining finish.

  3. #3

    Default Re: Finish delaminating National RM-1

    Dan, you didn’t do it!
    Adhesion is a complicated subject, but the problem started at the factory almost certainly. Many potential causes, like spraying conditions, mixtures, surface preparation, contamination of under-layers, etc.
    There is nothing you should slather on that will take off polyester that won’t mess up what’s under it, so the most probable educated opinion is refinish back to bare wood by sanding. While DIY possible, this is extreme, and at least in furniture, the end of monetary value!
    Since the ad I saw for the RM 1 says ‘satin polyester’, perhaps the better part of valor is just to protect the peeled places with something satin and benign, like a wax until you’re sure nothing else is going to peel, since there’s no way to predict if the problem is spotty or all over. The finish isn’t the sound, as far as I know.

    I took a chance a few weeks ago with a tourist-grade baglama or saz I bought for fun. It arrived with hand-sized peeled gloss areas over what looked like bare wood. Probably a polyester, or at least alcohol wouldn’t touch it. Asked for advice here. Too exotic a request! So I Scothbrited the edges of the peel to detach anything loose, and swabbed on some furniture gloss urethane with a little watercolor pigment stirred in. Surprisingly decent result; holding up so far. Your instrument is, of course, far worthier of respect and care, so wait for our professionals to chime in —- and call National too.

  4. #4
    Registered User Greg Mirken's Avatar
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    Default Re: Finish delaminating National RM-1

    Dan, you need to call National Resophonic and see if you can email them some photos. Don't put anything like wax on it.
    I suspect moisture has migrated into the bottom of the case. That would also explain the spot on the peghead, also near the bottom of the case.
    This is not an inexpensive instrument, and unless you have some experience with instrument finishing I wouldn't recommend DIY fixes.
    Shade Tree Fretted Instrument Repair, retired
    Nevada City, California

  5. #5
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    Default Re: Finish delaminating National RM-1

    I sent these to National, too...
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  6. #6
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    Default Re: Finish delaminating National RM-1

    Yikes! Sorry!

  7. #7

    Default Re: Finish delaminating National RM-1

    There’s a similar known issue with some National guitars. My recall is it was a bad batch of grain filler. Regardless, you have a great instrument.

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