Hard Color

Re: Anodizing Aluminum, where went wrong?

Where am i goin wrong guys? I am trying to anodize the clutch lever on my yamaha motorcycle, but it will not take color and i dont know if it even took any anodizing. I am using the battery charger method if you are familiar with it. These were my steps:

1. rinsed part in muratic acid to ensure perfectly clean.
2. used 14ga alum wire to hang part in a solution of
3. 50% premixed battery acid, 50% water
4. which should of gave me about a 20% sulfuric acid solution.
5. had lead for neg in solution and attached battery charger to lead
6. attached positive to aluminum rod that part was hanging off of
7. turned charger on and the lead ground bubbles alot
8. my bushing in the part dissolved quickly (ok b/c old bent lever used for test)
9. left on for 20 min until neg stopped bubbling and
10. the charger showed zero current was being drawn
11. took part out and rinsed in cold water
12. dipped in Rit black dye for 15 min
13. rinsed off in water and it looked just like i started!

Do you guys have any ideas of where i went wrong, or of where i could look for a better process? I would really like to figure this out , it is driving me nuts. Some teenagers are doing this and i cant even get it...:confused:

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Hard Color

Re: Anodizing Aluminum, where went wrong?

ok i just found a different "how to" online that says that i need 3 parts water to 1 part battery acid to get 20%. a differnt place said 50/50 and even another said 2 parts battery acid to 1 part water!! Ahh my head!!

edit: ok wikipedia says battery acid is 33.5%, battery acid (used in lead-acid batteries) (pH 0.5).

That means a 1/1 ratio of water/battery acid should of been right on. hmm. At least i am learning. This is a fun new challenge for me.

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Re: Anodizing Aluminum, where went wrong?


Yeah... you will find that. Hopfully one of our many experts that visit our forums will be able to help your with you problem.

Griffe Youngleson

Visit us on the web at:

Hard Color

Re: Anodizing Aluminum, where went wrong?

Ok guys, i decided to go with LCD anodizing per the caswell instructions. I ordered up thier dyes and got a CC/CV power source off ebay. When everything gets here i will try again with that method.

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Re: Anodizing Aluminum, where went wrong?

Most dyes are sensitive to temperature and pH. Check to make sure these 2 components are within the recommended ranges per the technical data sheets that should have been included with the dyes.
Also, you said you clean with muriatic acid. This will remove metallic contamination from the surface (oxides, etc.), but not organics like soils, fingerprints, etc. Need to preclean in a detergent based cleaner to remove these contaminants. Make sure the cleaner is not caustic based, or will etch or dissolve the aluminum. May also want to include a deoxidizer prep to remove any smut that could be present on the surface. 50% nitric acid works well. There are also proprietary deoxidizers on the market.

Welcome to the forum!

Hard Color

Re: Anodizing Aluminum, where went wrong?

muratic acid attacks aluminum the same as other metals correct? so shouldnt muratic acid work as an etcher also?

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Ryan Cook

Re: Anodizing Aluminum, where went wrong?

lets do this..

Go to the kitchen..  get out the big old bottle of dish detergent..   Dawn, Joy.  ETC..  all have a great deal of surfactants and emulsifiers in them that will rid your not so pristine clutch handle of any dirt, oil, grease.

if you can heat the solution great!  heat to @ 130 degrees and soak it for 10-15 minutes aggitating the part occasionally.

Next rinse the part really good and prepare to anodize it..

The concentration of the bath should be about a 15% sulfuric acid solution. at around 70 degrees.

Lead cathode will work but make sure your cathode is at least 2 times the size of your part.

Anodize the part at 16 volts for about 45 minutes and you SHOULD achieve a thickness of at least .7 mils, 

Rinse the part thoroughly as any acid left in the anodic pores will ruin the dying process you are about to perform.


not yet anyways.

Your dye tank should be at a generic PH of 5.5  at 130 degrees. (each dye is different, tech data sheets are great to find parameters)

dye the part for at least 10 minutes.  longer for lower tempratures.

finally you will need a boiling pot of Distilled/Deionized water  submerge your freshly dyed/rinsed off handel in the boiling DI water for a minimum of 30 minutes

(this is the poor boys style of sealing the anodized coating, crude but effective.)

voila you should have a good black anodized part. 

post your findings here and feel free to contact me at

Ryan.cook@teammetalfinishing.com :cool:


Re: Anodizing Aluminum, where went wrong?

Sounds like you did not have a good connection to the part.

John hu

Re: Anodizing Aluminum, where went wrong?

your problem seems to me lies in no control of anodizing temperature.
anodizing is a competetive process, electric Current makes the anodizing thickness grow while electrolyte consumes the layer of anodizing.
As during anodizing, lots of heat released, it will make the solution temperature go up quickly if no chilling system there, and higher temperature in the solution consumes the anodizing layer more faster. if the speed of consuming is faster than that of growing, there will no anodizing layer.


Re: Anodizing Aluminum, where went wrong?

If you have a conductivity tester, you can test for the presence of a non-conductive layer (ie the anodized aluminum oxide layer).  I've seen them at Harbor Freight for about $10.  It looks like an ice pick with a light in the handle and a wire lead with an alligator clip attached. 

To make sure that the part is clean before anodizing, do a water break test.  Remove the part from your rinse after the acid and see if the water beads up or breaks.  On a clean part, the water should sheet perfectly.  If there is any debris or oils, the water will break or bead up (just like a freshly waxed car).

Make sure that your anodizing acid is cold.  When you mix up the acid and water, you will generate heat and the bath will be too hot to use for anodizing.  70F is generally considered the optimum temp for anodizing.  As the temperature increases, the anodizing layer starts to be consumed during the process.  At a high enough temp, the oxide is dissolved at fast as it is formed.  An aquarium chiller can help keep the temps down for those of us on a budget.  Just be aware that the acid can and will eat up the internals of the aquarium chiller unless they can withstand the acid.

Heating the dye can speed the penetration of the dye into the pores of the oxide layer.  There is a limit, of course, but around 130-140 is pretty common.

Your power supply may be undersized for the part.  I'd imagine that the shift lever is no more than 0.25 square feet of surface area, which needs about 3-4 amps of constant current.

-Dustin Gebhardt, CEF

Advanced Manufacturing/Finishing Engineer


Sanford, NC


Re: Anodizing Aluminum, where went wrong?

Why can I not repeat the process

I had great success aodizing a single piece of ali 1 inch sq at 175 ma for 1 hour, rinsed and rinsed again, soaked in dye for 30 minutes, boiled for 45...beautiful :)


tried the above process with the same bit of metal, this time only filed the anodizing away to reveal virgin material, increased the size of the lead..but nothing happens, metal only turns grey after boiling,
Tried same process with other bits of metal, used a different power supply, checked temperature, distance of anode and cathode, polarity..even "over " cleaned the work with ultrasonic, most bubbles at the lead....still no joy.
I notice there is a bit of crystalization at the acid waterline with the metal.I am using 2 litres of acid and fresh de ionised water every time to rince. Acid is same ..battery acid cut 50/50 wit DI water.
I store acid in a clear plastic container, outdoors, behind my shed from direct sunlight, I have also noticed that the acid colour is now clear instead of that very light yellow when first mixed.

Do I need to change the acid, dye after every job...this is extremely fstrating..please help
PS:this forum is not allowing me to open a new post


Re: Anodizing Aluminum, where went wrong?

When the bushing dissolved it probably consumed all the current, preventing anodizing and contaminating he bath.


Re: Anodizing Aluminum, where went wrong?

Am I just backward?

I thought electricity flows negative to positive. Thus the negative electrode hooks to the water acid and the positive hooks to the part.