would it be safe to line the inside of my reflector with some diamond mylar? or is this a no no has anyone else tried to do this before with something else?
thanks

I wouldn't think it's a good idea. The diamond mylar is backed by plastic and I bet it can get pretty hot so close to your lamp.

Plus I recon the benefits are probably fairly low, unless you are able to perfectly line the reflector with the mylar so it's really smooth.

Pointless and a potential fire hazard - the inside of the reflector will be designed to be as reflective as possible to start with.

Ok thanx chaps

If the reflector has lost it's shine you can always paint it in heat proof white paint, used to be a thread on overgrow about, there was a specific colour that was best but I cant remember what kind of white it was.