Huge Problem

[PBInferno]

Up until now I've been anodizing using constant voltage, and I've had good results, except for recently. So today I decided I would do a run using constant current.
I measured my surface area and found that it was approximately 1.76 square feet. Then, using the 720 rule, I calculated that the parts should run for 180 minutes at 7.04 amps (4asf).
So I put the parts in the tank after degreasing and deoxidizing, and set my power supply for 7 amps. The voltage started at 30 amps, and slowly dropped (when I left the shop about 15 minutes later, it was down to 27.1).
I made it back just in time to shut off the power supply at the 3 hour mark, and the voltage was at 24.3, which seemed absurdly high. I took the parts out and this is what I found:



Any ideas what happened / what went wrong?

[Empire03]

Im pretty new to this but from my knowledge you left the parts in to long.

[PBInferno]

Yeah, it sounded like it was too long, but its what the 720 rule said.
Also, I did dye some of the parts and they colors came out perfect.

[acidrain]

Looking at the pics, it looks like only small areas of the original ano was stripped. It looks like the original ano was clear. True?
If so, and only small areas were stripped, it makes sence that it would take massive voltage to pump those amps through that small of an area.
It's always a good idea to use an ohm meter to check for complete ano removal.

[PBInferno]

Original ano was actually blue. Parts were stripped with Caswell stripper and then checked with an ohm meter.

[acidrain]

Wow, that is really wierd. I've never seen that before.

[PBInferno]

Yeah, thats what everybody seems to be saying lol.

Does the voltage seem too high to you? What about the time, too long?

I'm gonna see if this will strip when I head back to the shop a little later.

[mkriegs]

The voltage is a lot higher than what I get and I even use a higher CD than that. I had the same problem once and it turned out that the parts weren't stripping completely, but you said that's not the case.

If that happened to me I would check the different areas of the part with an ohm meter and strip and reanodize the part. but thats just me

[fourkbmx]

i finally had white ano using caustic soda, and i was very sure this was a done deal, so i was trying to achieve what is shown on the pic but i ended up with the same problem as you, i think that my problem was the concentration of the caustic soda, also i think it was because my piece was pre anodized but what i dont understand is why the pre ano wasent completely removed, because the problem of the piece happened on the part i wasent completely ano clear.

[PBInferno]

Well I tried stripping one of the parts and the anodizing all stripped off, but the abnormal areas were still there. I'm gonna see if I can beadblast it off tomorrow without hurting the tolerances.

I'm also having an issue with my black HBL dye. The part will dye fine, but as soon as the part comes in contact with air, the black fades into a bronzy color. I mixed up a new batch of black dye, and the exact same thing happened. I don't have an issue like this with my other colors, and all dyes are at 140*.