We got front gates made about 3 years ago and the finished gates powder
coated in black. The finish was fairly matt rather than high gloss, and
they have been fine up until now. When the brighter evenings came along,
I began to notice they looked very dull and almost grey.

So tonight I went out, armed with a bucket with Flash in it and a sponge
pot scourer thing. I gave them a good wash but as they dried I realised
that it has made very little difference, apart from removing a bit of
grey-green dust from around the bottom.

They almost look like an old car that needs T-Cut. Is this the case, and
if so, would T-Cut for black cars be off any use?

A further point to this: if you scratch a tiny area with your nail, it
looks like there is a shiny surface underneath. the "scratch" mark stays
there, but if you rub it with your thumb is goes and looks evenly dull
again. Whatever this top layer is, is seems to smudge around in a circle
easily.

This has two implications:

1. This layer may be removeable if it is identifiable, but what is it?


2. If it can't be removed, will it cause a problem for painting over?


Any ideas on these specific points please?

Suzanne