On 27/07/2019 09:56, Harry Bloomfield wrote:
Rob Morley pretended :
On Thu, 25 Jul 2019 11:59:00 +0100
Andrew wrote:

There used to be something called 'Jewellers Rouge'

There still is - I bought some on eBay a few months back.* It's just
ferric oxide in a very fine powder form.

Absolutely any fine abrasive polish will work, including toothpaste. If
the lens is in really poor condition, then begin with a fine wet and dry
paper, plus water. Don't use a drill or similar, except slowly with
water spray to keep it cool. Polycarbonate is easy to melt with too much
heat from friction.

There is still the problem of once they are clear and sparkely, they
will not remain that way for long, once the UV gets at them. They are
obviously protected by some means when they leave the factory, but that
wears of eventually. The best idea I have heard suggested spraying them
once polished up, with the clear lacquer as used on car paint work.

I have never had the courage to risk my lenses with that, but has anyone
tried it? What does the panel think?

The advice was never paint a polycarb crash helmet.

Followed by never put stickers on polycarb crash helmets.

The reason being that you can never tell what solvents are in the paint
or glue and what effect they have on polycarb.