I was rather sceptical about the ability of sand-blasting to work
harden metal, until I had an accident with a grill pan.
The enamelled grill pan assembly contains an aluminium insert and a
steel grill. The insert is a simple pressing made from 0.6mm (23
SWG) aluminium sheet. The pressing is just to create some
corrugations to add rigidity.
The grill is in the top oven and the accident occurred when I turned
the wrong oven to maximum and left it like that for an hour or so.
The insert was badly discoloured, and amazingly soft. The oven did a
really good job of annealing the aluminium.
I tried to abrade the discolouration, to no effect; the aluminium
was so soft that it simply distorted as soon as I applied any finger
pressure. I was unable to buy a new insert so, in desperation,
decided to use aggressive sand-blasting to remove the staining, and
just put up with the softness.
The sand-blasting removed the staining very effectively, but, to my
great surprise, also restored the original stiffness. The surface
was left as a matt finish.
Regards, Gary Wooding