Exactly what is dissolution?

[texsol]

sorry for the noob question but exactly what is dissolution?

[sswee]

Dissolution is the electrolyte disolving the coating. It occurrs throughout the process. It's beneficial to a degree by opening the pores up to accept more dye and giving better color. It starts to become a problem shortly after PAR (peak anodic resistance) when the growth of the coating slows to a point that it is disolving faster than it can grow. After this point the pores can enlarge to where they will not hold dye and the top layer of the coating is soft and crumbling. It appears as a white haze or film over the part. SS

[texsol]

Thanks, so if my ano tank is 20% acid and I'm getting a white haze on my part then I might have too much dissolution?

[sswee]

Yes. Acid concentration for LCD is 5%. SS

[texsol]

ok, but i want to anodize at 12 amps per square foot. Could you please tell me what my acid content should be. I'm sorry if this sounded a little mean I could not think of a way to word it.



Thanks, daniel

[sswee]

No problem. It's hard to hear the typing on how it's meant, no offense taken. I use a 8A CD because of PS limitations. I have been told the LCD mix of 5% acid will work up to a 12A CD. After that a higher concentration is better. SS

[RedRiver]

I use 9.8% acid / 90.2% DI Water (by volume) for 12-15 ASF.

[neilfj]

Originally Posted by sswee

No problem. It's hard to hear the typing on how it's meant, no offense taken. I use a 8A CD because of PS limitations. I have been told the LCD mix of 5% acid will work up to a 12A CD. After that a higher concentration is better. SS

I'm Back! []

sswee, 5% acid was successfully tested up to 24A CD with no ill effects. The main issue with higher current usage is that it requires very agressive agitation or aeration to disperse the heat and to make sure hydrogen bubbles don't cling to the workpiece. In fact, just before Paul had passed away, we had begun testing using chilling equipment to assist in the heat dissipation.

We didn't really publicize the higher current usage to any great extent as it began to push the definition of Low Current.