Letter 37017

Changing Anodizing color? [Florida] 

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Hello, my name is Steve. I am an Aerospace Engineer Major at Embry Riddle Aeronautical University in my Junior year. In my spare time a play paintball. I have been looking into anodizing some parts on my gun myself instead of spending a few hundred dollars to have someone else do it.

My problem is that the parts I want to anodize already have a black anodize on them. My question is if I can simply anodize a new color over the black or if I will have to remove the old ano first? If I did need to remove it, I could use the chem lab on campus, but I am not exactly sure of the best way to do so without damaging the aluminum parts.

I would also consider powder coating over the existing black, but I am not exactly sure of the process. Whatever I do, I plan on using the chem lab and practicing on some spare parts first. Thanks.

Steve Short
student/hobbyist - Holly Hill, Florida, United States

To do a good job, the equipment will cost several hundred dollars, and then you have the haz waste to dispose at a very high cost.
You can do an internet search and find all kinds of ways people have tried to do garage anodizing. some have good luck (so they say) and others have terrible luck. The main problems, is you need a controllable power source. A 12 volt battery charger simply will not do as good a job as something that you can ramp up to 15 volts and has enough amperage to not blow it up on the initial surge and has the amperage to get the part anodizing rapidly enough that you can raise the power to the final voltage in a matter of about 3 minutes.
Next, it generates a lot of heat. Decorative anodizing needs a constant temperature of about 72F, so you need some method of regulating the temperature. No, you can not put ice cubes in the tank.
The dye step requires a given concentration, temperature and pH. Rit Dye [link is to product info at Joann Fabrics] may work in some cases, but do not expect a permanent color.
Boiling DI water is a decent seal, but a nickel acetate seal is more permanent.
NO, you can not anodize over the existing anodize. It has to be stripped. When you strip the old anodize, you will remove about a thousants of an inch from the existing size.This is going to affect the fit and function of the weapon, some. Your gun may be clear coated or waxed. This gives several more challenges to be overcome.
Spend the money and have more time to enjoy your painball hobby. On second thought, the beautiful gun will not work a bit better. Spend the time and money on practice and become a winner.

James Watts
- FL

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