On Wed, 17 Apr 2019 13:09:47 +0100, newshound wrote:

On 17/04/2019 11:20, Roger Mills wrote:
The prescription specs which I use for computer-based activities have a
scuff mark about the size a finger-print from a little finger on one of
the (plastic) lenses.

Whilst I could buy a new lens for £30 or so, I've been trying to polish
it out on a DIY basis.

I tried Brasso but didn't do a lot because the blemish was a bit too
deep. I then rubbed the area very gently with very fine wet & dry, used
wet. This got rid of the scratches, but left the area looking like
frosted glass. I've improved it quite a lot by buffing it with a
dremel-like tool, using a buffing paste made from olive oil and talcum
powder (how DIY can you get!) followed by a further application of
Brasso. The affected area is still a bit blurry.

Any ideas of what else to try?

One thing to watch, assuming it is a plastic lens, is if you use a
Dremel at too high speed or load the temperature rise can distort the
lens. You will only be able to tell when you try looking through it.

DAMHIK.

Yeah, YJD... :-)

That's *not* the bad news when using a high speed polisher on *plastic*
lenses. The bad news is the localised surface melting from the use of
such high speed polishing efforts. Even over-vigorous manual application
of a polishing rag can melt the surface, completely defeating the whole
polishing enterprise (i.e. damaging the surface beyond any such
redemption).

Plastic surfaces can be polished successfully but it is fraught with
this low temperature melting issue that simply doesn't exist with
traditional materials such as glass and most metals in common use.

Whilst the polishing technique is basically the same for plastics and
traditional materials, you have to keep the very low melting points of
most plastics in mind and dial back the polishing effort somewhat
compared to what you may be used to using with glass and metals.

--
Johnny B Good