I've found that aluminium wire can work OK if you use a fresh piece each time and make sure that the part can't move on the hanger during anodising (i.e. tightly wedged, screwed, etc.). Once it's been in the bath a few minutes, anything that isn't in direct contact with the part will be anodised enough to prevent good electrical contact as per @hotponyshoes' post.I have tig'd some alu filler rods to use as the electrical connection, poor connection may have been a problem last time.
T'other way around - as resistance increases it takes more voltage to maintain the same current (says a pedant) - so there's a surge current at the start, until the oxide layer starts to form.No, because you don't need much current to maintain the voltage at the start.
As the resistance increases your power supply is providing more and more current to try and maintain the same voltage.
T'other way around - as resistance increases it takes more voltage to maintain the same current (says a pedant) - so there's a surge current at the start, until the oxide layer starts to form.
Dave H. (the other one)
P.S. - Asda's cheapest black inkjet refill gives a lovely coppery-bronze colour...
Interesting. I need to make up a load of test pieces.P.S. - Asda's cheapest black inkjet refill gives a lovely coppery-bronze colour...
Yep, so when resistance is low (before the oxide film builds) there's high current (volts = amps × ohms), once the oxide forms resistance high, current low - constant voltage, has to work that way.Yes but the op is using a constant voltage supply so the voltage is fixed.
That is what electrical theory dictates should happen, but it did not. I'd like to understand why. It might be a large pore size and surface area with little oxide, but it took colour well and sealed ok.Yep, so when resistance is low (before the oxide film builds) there's high current (volts = amps × ohms), once the oxide forms resistance high, current low - constant voltage, has to work that way.