Lacquer Finish On A 1980 ST80

[Sigmania]

I just read in Japan Vintage Vol. 2 from 2003 that the lacquer finish on these was applied over a thin layer of poly...

"It is coated with a thin poly coat and then lacquered. In rare cases, there are those that do not have a poly paint coating or have a very thin coating." (Disassembly of a 1980 ST80 GSR).

That would explain the mixed results in acetone tests on these over the years...

 

[Homer J. Simpson]

AFAIK that's similar* to what Fender started to do in the late 50s as well. Not to mention the "Fullerplast" sealer underneath, beginning in 1956 Dupont started transitioning many of their colors to the more stable acrylic binder, so more and more color coats were acrylic while lacquer was sprayed as a top coat until around 1968. Source

By the time Fender reacted to the vintage craze by using NC lacquer top coats on selected models again, usage of acrylic binder had gone out of fashion and polyurethane color coats went underneath the lacquer. AFAIK this is basically today's standard for guitars from F+G advertised as "NC finish". According to the page linked above, the history in between seems to contain nasty episodes and true loopings (lacquer color coats with PU top coats). The nastiest part of it was the introduction of polyester, and it always irks me when people do not distinguish between PU and PE, which might be the only cause for the bad reputation of PU and the weird but lucrative hype around NC lacquer.

 

[Sigmania]

Thanks. Good info!

So, I am now wondering if the top coat of lacquer would have been applied as fully as the base coat? In other words, is it possible that when someone tests in a pickup cavity would they be getting a good representation of what the rest of the guitar is coated with?

The article also said that in some cases Tokai just used lacquer rather than a thin poly base coat.

Fascinating.

 

[Homer J. Simpson]

If I understood that right, lacquer requires an absolute minimum of 3 coats (on furniture, likely much more on guitars) with hours of drying in between, that's why it quickly went out of favor in mass production (at a time when nobody thought about about the health implications yet and workers sprayed that stuff w/o masks). It seems logical (to me) that more coats = less chance to miss a cavity so thoroughly that the acetone test would reliably fail.

But I can imagine that people may also do the test with wrong expectations: When you don't know that only the (clear) top coat is NC and you expect getting some color rub off on your cotton swab, and the coarse wood grain in the cavity is making it hard to see an impact on the clear coat residue in there... I guess that easily could lead to a "false negative".