UV, Poly-urthrene, Poly-ester finishes

 
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In our previous article titled: Polyurthrene & Epoxy that article discussed the differences
between these finish types used commonly by the factories in guitar making.
 
This article briefly examines the ongoing research we're doing on the three top finishing products:
UV, Polyurthrene, and Lacquer.
 
To demystify "UV," it's a polyester product that is coated to an instrument (mostly guitars)
then cured by "ultra-violet" lighting thus the term "UV."
 
Comparatively, Polyurthrene is a two component product similar to an epoxy found
at the local hardware store. That is, you mix part "A" with part "B" and it will harden
thus polyurthrene is a reactive procuct. The two components come together and react chemically.
 
Urthrene mixed with polyester becomes the product applied to guitars and other instruments
that is cured by "UV" lighting as mentioned above so its reactive also. This mix/product is done by a manufactuerer
and is not available (to our knowledge) at your local hardware depot.
 
Meanwhile, the old reliables such as lacquer or shellac finishes are solvent based.
This means there's no chemical reaction or a third part to get a reaction such as
ultra violet lighting.
 
Lacquer and shellac (used in French polishing) expoliates or evaporates via a
natural curing process. That is, the product component evaporates into air and
begins to cure to a harden state.
 
Recently speaking with SPD's engineer who is a maker of "UV" products (Polyester)
he reminded us that no finishing product will ever find its cure point. That is, there will
never by a point that the product is rock hard, but the "Poly" products get to a cure point
faster then lacquer or shellac and give the feel of a rock hard glass like (or wet) finish.
 
The thing is that when a poly is damaged, chipped, or what have you making a repair
is almost impossible unless you start the process from scratch. However, with lacquer or
shellac these products are foregiving and blend into each other. Thus, finish damages
can be repaired.
 
Moreover, soundwise, lacquer and shellac give the best result in sound whether a violin,
guitar, uke, cello, or even a piano's sound board.
 
In sum, using the "Poly" family products is cost effective for instrument makers. Its cheaper
then shellac or lacquer and it gets to a hardening point faster. So when a factory is producing
500+ instruments per week curing an instrument with UV or Polyurthrene they get immediate
results as opposed to waiting for solvents to expoliate then getting to buffing and asembly.
Simply stated: Cost/Benefit.