Anodizing tank time

[Fibergeek]

Heed M_D's warning about native oxide; you usually can't see it, but it certainly can foul you up.

Regarding your setup:

By "current limiting power supply"; I hope you mean a constant current power supply, it has adjustment knobs to vary the voltage AND the current. Most all fixed power supplies have some form of current limiting, but this only works at the max power limit for the supply, which won't do.

Be suspicious of you connection method to the work; some here have a method like yours working, but they usually thread the wire and the hole. An incomplete thread on either helps the wire cold flow, which forms the required liquid tight joint. You may want to bolt the wire to the work (aluminum hardware) until at least you get things sorted out. You want to crush the wire under the bolt.

Cathode shadow is caused by improper cathode placement for the tank geometry. You might try not running the cathode across the bottom but on all four sides instead. You also must also have at least 3 inches from the work to any cathode surface or shadow effects can appear.

[elton10]

Mike suggested I post this to the forum:
How can I speed up the process so that we're not spending 90 mins to anodize each batch?

Can I go to 6 A ft 2^.. will that reduce the time proportionately (i.e. from 90 mins to 60).

thanks in advance

Elton

[Fibergeek]

You certainly can.

Recall that the published LCD range is 3 to 6 A/sq.ft. 4.5 A/sq.ft. is in the baseline LCD instructions because its the exact middle of the LCD range. I know this because I selected it.

Anodic coating growth is proportional to both anodizing time and current density. Its almost linear if electrolyte temperature is held constant and the dissolution rate isn't excessive.

The upper limit (6 A/sq.ft.) was selected for four reasons:

1. In most Caswell kit scale anodizing the power dissipated in the electrolyte is still low enough not to require temperature control. (Equipment costs.)

2. The peak voltage is still low enough to permit a typical battery charger. (More equipment costs.)

3. Lower current density is more forgiving about agitation requirements. You still have to have it, but its not as important that it be real good. (Yet more equipment costs.)

4. Pore size is about optimum for easy and excellent dyeing with the (safer than traditional concentration) 5% (vol.) LCD electrolyte.

Some of you here have acquired the skills, knowledge, and experience to rightly be called "small scale" anodizers, you aren't "amateurs" or "hobbyists" anymore in terms of the results you are consistently getting. The patience you show and help you make available to the less experienced guys is appreciated.