I have a late 60's Ludwig set with a little fade on the bass- I can't tell how long it would take but having painted autos know that an unprotected acrylic enamel finish in ONE Summer's sun will start to fade. (that is - no wax or shade) I also know that I rewrapped an old set in WMP and put it in my van to take to a gig/ had bags for all but the 13" tom on the front seat. Talked to a friend in the parking lot too long as the sun beat down on it and- had bubbles in the wrap later- was able to press them out but- careful now putting ANYTHING in direct sun for long.... when we play outdoor Summer gigs in early evening I take my old Japanese kit! Keep it outta the sun!