Kick-starting this puppy back to life after several comments about finishes in another thread:
http://www.letstalkguild.com/ltg/sh...-leaving-Guild&p=1737462&posted=1#post1737462
The aging part if you ask me haha yeah it will look all shiney and new if you don't use it . My old Yamaha was poly and she aged wood wise now I had it outside a lot in the sun over the yrs she turned a nice Amber color that was in Florida beach side . Should have never sold it ,
If it will get beat up looking and the top can still color change and deliver great tone that works for me better then a kracle glass collection on my guitar . But hey talk about it anymore they have crack resistant NCL Yaaaaaay
I might be doing a NCL repair as my Cv fell over and chip in between the tuner and the NCL Is stained now that gets my goat ��
And lemme reiterate the whole point is to explore the pros and cons of the various finishes without trying to prove one is "best", in spite of personal preferences.
Hey, I might wind up getting converted myself.
:friendly_wink:
So...getting back to the original point, Guild's now using 2 finishes for sure: "catalyzed varnish" and traditional NCL.
Let's make very clear that a unique property of of true NCL lacquer is that readily dissolves and blends if new NCL applied over it, it's its own solvent and crystallizes much like hide glue (or amber or pine resin) does as it dries.
Any of the water-based lacquers won't be chemically identical; on drying, NCL is only re-soluble with organic solvents, which are the "VOC" 's that are the primary environmental concern.
Nitrocellulose is insoluble in water therefore any lacquer that's waterbased cannot be an NC type and I suspect they're acrylic lacquers.
Which aren't re-soluble like NCL.
Here's an interesting discussion about the state of waterborne finishes from a banjo forum in '09:
http://www.banjohangout.org/archive/149219
Consensus seems to be that water-based is still somewhat inferior to what they call "spirit-based" lacquers, recognizing that was 7 years ago.
Let's make it clear that poly
urethane based finishes aren't very eco-friendly either, releasing large amounts of formaldehyde as the cure and in fact the expandable poly foam that used to be so popular for conformal cushioning packaging up until the late '70's was one of the first targets of environmental regs. That's why you don't see it anymore, in the USA.
Essentially the issue with "polys" as a generic class is that they are chemically catalyzed and once the catalyzation is complete, that's it, no more evolution of the finish.
Is that a good or a bad thing?
The only "real" "bad" I can think of is difficulty of repair if needed.
Varnish:
As mentioned is a generic term for a protective coating but traditional instrument types are chemically is closer to NCL than polys as they also continue to evolve as they age.
Guild's use of the term "self-catalyzing" definitely means that their varnish carries a catalyzing as it's applied, the inference being that it needs no more than some air curing time, as opposed to the increasingly common UV-curing technique used on "true" polys.
It is possible to repair poly. Taylor has a course on how to do it with their finish. Doing it without leaving any witness lines is a whole different story. It is extremely difficult. Poly finisheS, after the catalyst has done its job, cannot be un-catalysed....
Once the catalyst is consumed in the process of hardening the poly finish, the poly finish is done, it won't change chemically in any way. Nitro continually outgasses, getting thinner with the passage of time. The other part of this is that nitro also crystallizes, meaning the out-gassing of the solvents leaves solids behind, These solids tend to improve the tone of the guitar. While it may look to be very hard, poly is actually somewhat flexible, and doesn't change over time as discussed above. This acts as a very slight tonal absorption. That will NOT get better with time
Here's where I think the real "tone question" comes in:
In at least a couple of sources (the one I linked above and this one Ray cited
http://proguitarshop.com/andyscorner/nitro-vs-poly ) that varnish and NCL lacquer is actually "softer" than poly and that a certain amount of flexibility is actually desirable.
So I get that yes the finish needs to be able to expand and contract with the wood's humidity fluctuations, and in the case of a varnish finished cello especially, the whole top is actually a giant speaker cone after all, and it does need to be able to vibrate as freely as possible, and it seems that poly, no matter how thin, would tend to inhibit that as it's far less "stretchable" than traditional oil varnish or NCL.
Perhaps poly
ester based finishes (which are really the norm for guitars right now as I understand it) do offer a degree of "flexibilty" even though their surfaces are supposed to be "harder"?
That does tend to contradict my traditional understanding of Kostas' point that NCL hardens and gets more resonant, but perhaps the 2 issues should be addressed as an interacting phenomena with NCL, which isn't present with the other 2 finishes?