lifespan of lightscribe discs

Ive been using lightscribe discs for a few years now and as im going back to use some of the discs I burned a long time ago(1 year+) im noticing there is a weird white powder layer thats forming on the top side of the discs, I have used both verbatim and HP lightscribe discs and both have that weird whitish residue on tops, it can be wiped off with your finger then you can see the powdery residue on your finger .I even kept them in disc binders and they still have it.Not only that some of the disc I first burned are actually fading so bad its tough to actually make out what they say still. Just wondering if anyone else is having issues with them and if there are any fixes.So far I have polished teh tops of tehm with silicon cloths as to leave a thin protective layer and maybe keep them from oxidizing further if thats whats happening.Any thoughts would be appreciated