Guy King wrote:
The message . com
from "Aidan" contains these words:

I think caustic soda would just dissolve the aluminium.

It does if you leave it in too long, but I've done it - oddly, from a
suggestion in a very old electronics mag, and a pint of warm water
with a tablespoon full of caustic soda in it does produce a passable
finish.

Anodising it is not - nor is it a patch on proper anodising, but it's
OK for some uses.

John Haigh mode on
but where can I obtain Sulphuric Acid?

--
Sir Benjamin Middlethwaite