Best anodizing guide?

[Zeeflyboy]

Calculated for my part 25V max, 2.7A for 72 mins.

Sounds like he is using a constant current supply if he is able to set 2.7 amps... I assume you are using 6 asf and then using your cad program to determine surface area of the part multiplied by the number of parts being done at once to arrive at the result?

From my research I've seen suggested that for 6 ASF you are looking at something around 1:15 acid to water ratio (6.7%), so actually if anything yours sounds significantly too strong. Caswell only mention battery acid (usually around 32%) at 3:1 with their 4.5 ASF, so unless my maths fails me that would be an actual acid/water ratio of around 1:11 or roughly 9%, again making your mixture far too strong if using their 4.5asf method. Oddly enough that should result in a larger pore size however... perhaps you actually end up with pores too large to hold on to the dye? Conversely the excess acid concentration may mean that it is breaking down as fast as it builds up, leaving you with an insufficient anodised layer.

I would suggest you adjust your solution to the correct strength and see how it goes.

Also don't submerge crocodile clips into the bath, no metals other than the lead/alu cathodes and alu/titanium wires/rods should be in contact with the acid solution. Other than potentially contaminating the bath, the current will try to flow through the steel clips instead of the aluminium and your anodising will stop.