So just trying to understand this long talked about issue. You state UV light exposure is the root cause of fading. Would you go as far to say to blue pigmented guitars only? I appears none of the other colors are effect to the degree that the blue ( and variations) are just an observation. I own five core guitars going back to 1990 and none have faded in any form. Disclaimer none are blue! My brother owns three going back to 1986 all blue the 86 has faded slightly however the 92 custom mix color ( when you could ask the dealer to get a custom color) has faded to a completely different blue. Originally it was more of a Cobalt color. Thanks
Organic dyes are photosensitive. They will react to light - not just UV, photons being photons, though UV causes the worst problems - that is their drawback. However, inorganic dyes are not transparent.
If the object is to see the grain of the wood, then you have to use organic dyes.
There is no magic bullet or "fix" for what is the very
essence of the dye, i.e., organic chemicals in its composition. "Fixing" this would mean that blue PRS Guitars would be opaque, not transparent.
Blue dyes seem to be the most photosensitive. In fact, blue and purple dyes were created in the ancient world by leaving certain snail parts to lay out in the sun to change color (which, incidentally, was reputed to create a very bad smelling situation for those making the dyes!). As you probably know, the same kinds of dyes were used in the red bursts on the old Gibson bursts, and they changed color to become brown. It happens.
Nonetheless, if you keep even blue guitars cased when not in use, as opposed to hanging on a wall where natural and artificial light hit the guitar, the fading doesn't happen very much, if at all.
There is another benefit of keeping a guitar cased: Cases act as a buffer against temperature and humidity changes - meaning you don't have to make as many seasonal setup adjustments, and keeping them cased also prevents the stuff in the air (like cooking oils that float throughout homes and create stickiness in pots and switches, which attract dust and impede signal flow, f'rinstance scratchy pots) from landing on the guitar and causing problems.
So there are three good reasons to use a case.
I have two blue PRSes. One is a 5 year old PS in the notoriously fade-prone, blue and violet "Northern Lights" finish, the other one is a 2021. I keep them cased. The Northern Lights guitar is vibrant and hasn't faded in any way.
If you want to preserve the finish, keep the guitar cased and enjoy the other benefits.
