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Anodizing problems: paintball guns

Me and a friend have recently started to try and anodize our paintball guns. we have a 3 gal tank mixed about 18% acid to water ratio. we have a manual battery charger ⇦this on eBay or Amazon [affil links] that run 12v 10 amps. for our cathodes we have aluminum sheeting that is 6063. we hooked everything up and tried our first piece, leaving it in the solution for 90 mins on 12v/10 amps. it worked great, it came out a nice red.
We successfully completed the process 2 more times. after that the pieces started coming out more and more faded till eventually they won't hardly hold any color. started from scratch and mixed another batch of acid solution and cut fresh cathodes. it worked fine again for a few pieces but did the same thing. any info would be much appreciated.

thanks, Martin.

Martin perez
anodizing - Rocky Point, North Carolina
January 28, 2011

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12 volts is on the hairy edge of being able to anodize and get any significant deposition which is what it takes for the dye to take.
Your tank is small and that means that drag in and drag out are potential problems. As you anodize at a minimal voltage, the aluminum content builds up faster than normal which means that the quality of the anodize will drop quite rapidly.

I think that the solution is to get a better power source and one with a variable voltage output. It is a bit of a shock to the system to drop in a part at full voltage at the start. Several anodize references say to ramp up the voltage, basically at a constant current (amperage).

James Watts
- Navarre, Florida
First of two simultaneous responses -- February 1, 2011

Try hard or ordinary lead cathodes.Hope it helps and good luck!

Goran Budija
- Cerovski vrh Croatia
Second of two simultaneous responses -- February 2, 2011