Bowers and Wilkins Kevlar Age Discoloration, Restore?

Kevlar is naturally yellow-gold when new.  Surface discoloration usually indicates UV degradation, which causes the colour to darken and reduced tensile strength.

Unfortunately, UV degradation cannot be reversed.  Kevlar should be shielded from direct sunlight .

I was thinking it was UV. I'm just going to keep the cover on. I'd be curious to see what will eventually happen to the D3-D4 silver fabric.

I’m only speculating, but the silver colour on the D3/4 could be a coating on the Kevlar to protect it from uv rays. 

The silver looks like just a decorative change. It would look nasty if it gets brown over time. It still feels the same but it's a thinner weave. There could be a coating but who knows. I'm thinking about buying either a spray or oil UV fabric protection.