Tony Burns said:Finish checking also comes with age -like fine wine i like it on my vintage instruments ! My 71' D-55 has a bit but very fine -probably from all those long walks in the cold when i was a Youngster !
This is what I was trying to get across on the "Nitro vs. Poly effects on tone". What I very badly wrote, and what actually relates to this topic, is that solvents in nitro continue to outgas until there are no more left. What is left behind is the original "lac" (sort of like tree amber), and it has no flexibility at all. This lack of flexbility (to match the wood expansion/contraction during temperature changes) is what results in lacquer checkng/crazing, and also what makes most people believe that nitro finished guitars sound "better" than poly finished guitars. The tendency to check/craze increases with the age of the nitro. The finish on poly finished guitars, once exposed to UV, or hase the catalysers "kick off" really doesn't change, ever. The poly is also far more flexible than nitro, especially as time goes on, which is why you don't/very rarely see checking/crazing on poly finished guitars.
Another way to think of this is take two sheets, one metal (representing aged nitro, i.e. no flexibility) and a rubber sheet (representing a poly finish). Hit them each. Which one will resonate more? Granted, an extreme example, but it actually fits the nitro vs. poly finish scenario, even if it is quite exaggerated.
Kostas