'?' for Fibergeek

[00_buckshot]

In some of your anodizing experimenting you attempted to anodize @ 12A/ft2 with a PAR of 2.5 Ohms. Your peak voltage was calculated @ 30V which your sample never reached. You stated, "If a means were provided to stop the rapid dissolution of the anodize layer on the 12A/ft2 sample, it too would have a thick anodize coating. Retarding the dissolution reaction so that the correct peak voltage can be reached is probably how Type III (hardcoat) coatings grown."

I just pulled this off of a company's site that does Type III anodizing:

What is a hardcoat anodizing?
This can be a vague term, but usually hardcoat refers to a very thick and hard anodic coating. This kind of anodizing is accomplished with a bath similar to the standard sulfuric process, but with the temperature reduced to about 0?C to slow the dissolution rate. A higher voltage is applied to enable the coating to continue to build after the insulation value of the coating starts slowing down the coating formation.

http://www.saf.com/anofaq.html#10

So, if you were to cool your bath to 32 Deg F and try this experiment again you would more than likely reach the peak voltage of 30V correct? What kind of dying properties do you believe this sample would have if is was allowed to grow it's full coating?

Thanks for the input.

[Fibergeek]

I don't think it would require a temperature that cold (0 deg. C) to get the 12A/sq.ft samples to full coating thickness, but I haven't tried it.

If the anodize were at full thickness dyeing properties should be very good. Increasing the acid concentration to increase pore size may also be necessary.

Type III (hardcoat) also requires much higher peak voltage to accomodate the very high current density. 100V peak is not out of the question. The thickness and density of Type III would show a value of PAR much higher than 2.5 Ohms/sq.ft., I don't know how high.