Dupont MD50 Guitar Finish Is MELTING!

flip-guitar

It may not be the bug repellant in isolation but the combination of the spray and excessive heat and humidity together? This may explain the q-tip test not causing problems.

flip-guitar

crookedpinky - another pure guess here but it could be that there was something like a small area that was not completely cleaned before finishing, some oily substance or similar, so the finish may never have properly cured on that patch

crookedpinky

Flip Guitar - that could makes sense but I suppose, short of having chemical analysis carried out (where's CSI when you need them) I don;t suppose I'll know for certain.

Al Watsky

I've been told two different things about the Dupont finishes, the first is from the Dupont site which implies that the more exclusive instruments have a "traditional" lacquer finish and the other bit of information was from Michael H.
He told me that the instruments are finished using a product with less VOC's , to conform to environmental laws.
He couldn't confirm or deny that it was a water bourn lacquer or not.
Usually if a finish reacts to solvents its high solid, and solvent based. Nitro finishes fall in to that category . So is you get your solvent on there , the bug spray or what ever, and for what its worth , the finish does not care if you sprayed it directly on there or rubbed it on with your forearm , will sometimes soften the finish enough to allow for the finish coat to actually sag and move, sometimes it will stay soft after the chemical bath and what you do is pad on a hardener or drying accelerator . You can pad on a product called Japan Dryer. Thats not the most gentle stuff but I have used it in the past on finishes that were contaminated by solvents and it has allowed the damaged finish to re dry, after which it can be sanded lightly for mechanical adhesion , no more than 800 grit if possible to avoid sanding through the finish, than you over spray. You could clean first with naphtha and then treat with Japan Dryer.
I have had cases where there was contamination of the finish due to incompatible fill mixtures for spanish cedar, but that would not be the case with the spruce top on a guitar as there isn't any fill used on that .
Another possibility is that like Collings , Dupont does the under coat in poly and the finish coat in nitro. This is highly possible. Its a very common method because it allows the manufacturer to claim that the finish is Traditional , while still having the ease of application and durability of poly.
Either way you will need to consolidate the remaining finish and over spray the area.
That being my take , with out pictures or hands on examination.

Al Watsky

Oh, and just for good measure.
Theres a thing that happens when factories add too much retarder to nitro mixes.
It never really hardens.
Can stay soft for decades. When that is the case any warm moist heat will reactivate the chemicals in the finish and it will stick to anything, a shirt sleeve , arm hair, whatever.
There is a company the I worked for, that will remain nameless, who had this problem all through the 70's .
So you could have that problem, its not impossible, if Dupont is overspraying with nitro as a finish coat.
Same fix.
Japan Dryer or the like and over spray.
If its not a tinted finish and it has a poly under coat you can always remove the contaminated finish coat with acetone and refinish in nitro.
I've done that in the past.
So you remove the contaminated or over retarded finish and reapply a finish coat.
That fix works best if you know you have a poly undercoat because the under coat is impervious to the acetone.
You need to know what your doing though.
Consult a professional if in doubt.

Bohemian

Automotive paint supply stores have a wealth of info on finishes and their failures..

Might try asking them.

guit-box

Does anyone know of an email contact for Dupont guitars? I'd like to contact them directly. Maybe they can tell me from the year and model which finish was used and if there had been problems with other guitars finished the same way.

pickitjohn

@guit-box

Not sure if you'll get your answer, but I would try this page...

http://www.acoustic-guitars.com/

email your request to ...
[email protected]

good luck

pick on

pickitjohn

guit-box

Thanks for the info. I sent them an email and we'll see what happens. The person who suggests that it's bug spray--I just want to say that I've had many GJ guitars and this has never happened and all of them have been to hot/humid/outdoor gigs with me over the past 12 years. My Dell Arte finish looks just like it did when I bought it. I've only owned one Dupont and have a friend with one and his looks even worse than mine and he says he's had problems with the finish getting soft on him. So, there *must* be something different about this finish.

Jazzaferri

@guit_box ........Did you hear back from DuPont?