Great anodising pictures!
Interesting that they use titanium and aluminium jigs.
Some contamination in the acid tank, trying to work out what it is! Maybe something left over from the walnut shell polishing stage.
The Cooper Calipers are actual Mini car calipers, One of the bosses owned a cooper and he made his own, then they started to sell them as spares to other enthusiasts, not many and not for long if I remember correctly
Thats the whole reason you have the name "mini" calipers from the early 2000's