Aluminum Anodizing

Black is the hardest to get right with a home setup. A few questions.

What grade of aluminum are you using?

Are any of the parts touching the cathode?

What material is the cathode?

Are you rinsing the parts in clean water between each process?

What type of dye are you using?

Are you agitating the cleaner, desmut, dye and sealer tanks?

What temps are the cleaner, desmut and dye tanks?

Nickle Acetate sealer works better than boiling water.

I get better results with black if the acid solution is 10% at 65F or below. I freeze Ziploc baggies filled with water and drop in the acid tank.

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I'm using 6061 aluminum
the parts are all suspended, mostly equal distance from the cathode, but there may be some that are a few millimeters higher just because they are smaller
the cathode is the same, 6061
i'm rinsing them with distilled water
using casewell dye
no agitation in any of the tanks... but i believe it shouldnt be hard to add if it makes a big difference, i have a large pump from my old aquaponics (vegetable/koi fish) setup
the temps are in the mid 70's the acid tank get up to about 79. i try to do it early morning before it gets hot outside, this setup is in a large storage shed.

i've been thinking about putting another tub full of ice under the acid bath.....
 
Here is a short write up I did for another group a few years ago that shows my original setup. It worked well but I have since changed the coolers to 3 gal buckets for ease of storage and added better heaters.

How good is the connection from the part to the suspension wire? You may not be getting good enough contact.
 

Attachments

  • Small home anodizing setup.pdf
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i'm wondering if the titanium wire holding my parts isnt the problem. they bolt on to the top cathode but have a J hook on bottom to hold the pieces.... i'm wondering if the J hook isnt providing sufficient contact and the pieces with best contact are getting the most current through them....
 
I have not used titanium wire but I know with soft aluminum wire (that has no spring to it) I have to get creative to make sure there is a good (tight) contact area between the wire and part.
 
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