Anodising Aluminium

Now for my exciting current project! I am learning the joys of Anodised aluminium.

My last lot of work came back from the anodisers with surface pitting, I was told it was the metal, although the previous pieces I had anodised were from the same sheet and they worked perfectly.
Supposedly there can be variations in the metal in the one sheet, this being the case my pieces have a random chance of working!
I did do some research today and found a site that recommended a bath of caustic soda and warm water to strip back an anodised surface. I tried the bath on the pitted versions. It worked great, I was hoping to clean them up and have them anodised again but the pitting is too deep in each one.