What's the best material for anodizing cathode?

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k_ozdragon

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Feb 14, 2015
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I'm trying to setup my first anodizing bath and am having some material issues. I see many people recommend using either aluminum or titanium plates as the cathode, but then I watched a great video on YouTube and the guy was using lead. I thought the lead was a great idea, but I dont know enough about this to be certain. I know titanium will build up a corrosive layer that affects its ability to properly transfer electricity, and that aluminum also does the same thing but at a much slower rate. So it seems to me that lead would be a better choice since it shouldn't build up any anodizing plus it won't release any corrosive contamination into the bath. What do you guys think? Also, when I looked up titanium anodes, I saw rhodium plated stuff as well as something called MMO plating. Do those work, and do they suffer the same issues as titanium and aluminum? I appreciate any input!
 
Might help if you told us what metal you are anodizing and in what electrolyte.
 
Aluminum and titanium in dilute of battery acid. Thought those were the only 2 besides niobium that could be anodized. If I recall, you plate items with the opposite polarities. I decided on sulphuric acid after watching a bunch of stuff and reading online that its basically the best electrolyte for the job. I know TSP and various other odd things work, but it seemed to have the best results.
 
Glad to help! I get most of my stuff from them- and they have complete starter kits pretty reasonably
 
What type of contact wire do you use to connect the part to be anodized? I ordered aluminum because I figured it would take longer to build up a corrosion layer that would affect its electrical resistance. Also it seems to be cheaper to replace when this occurs.
 
Commercially, Aluminum is anodized in Sulfuric Acid using Titanium racks and Lead cathodes. Rhodium and Platinum plated Titanium is used for auxiliary anodes on bipolar racks to throw electroplated Copper, Nickel, and Chrome into low current density areas (recesses).
 
Aluminum works fine but you have to throw it out each time. It also isn't good for making a spring connection. Nice when you want to screw it into a threaded hole in the part since it is softer than the part you are anodizing. Titanium rods .062 diam are what I use for most things. They last A long time through many uses and you can make clips and springs with them. Hardest part about anodizing is learning to make good part connections that stay secure throughout the process.
 
Ok cool. Looks like I need to get some titanium wire then. I guess I can just etch it when the layers build up too much. I already have some aluminum wire on the way, so I'll use it for a bit then switch. Hoping everything will work well when I go to do it. I'm sure there's fine tuning I need to figure out. Right now idk what to do about my power source. I'm broke, so thinking of going with a 5 amp 70 volt supply until I can afford the 3 amp 140volt one.
 
I have seen some pretty good DIY powersupplies online for titanium anodizing. For aluminum some people use a cheap battery charger for a while until they get a proper power supply.
 
Yeah I considered just using the basic cell charger for the aluminum lol. I've tried using 9v batteries hooked up to a potentiometer and a volt reader, but couldn't get consistent voltage necessary for doing titanium properly. If I remember correct, you only need 12v and 2 amps to do aluminum. I know for titanium the amps dont need to go over 1 amp but the voltage goes up to 160 for the various colors. I figured that the 70 volt supply would give me the most popular color range while remaining affordable (for now). I can't wait to set everything up and give it a try. Praying I'll get it right the first time lol. The link to those plates was the last piece of the puzzle. If anyone has any tips or tricks that I could use, please let me know!
 
With aluminum the amps are dependent on the surface area of the part. The 12 volts are ok, but I tend to be more around 15v. Depending on the size and number of your parts you could be anywhere from an amp or two to 20 or 30. Be sure to read up on the 720 rule before you start, will save you a lot of trouble!

http://www.caswellplating.com/720.html
 
Awesome, bookmarking it now. Yeah I've watched a bunch of videos and read everything I can on this, yet none of them quite seem to have all the information or can seem to agree on anything
 
tiguy7 said:
Commercially, Aluminum is anodized in Sulfuric Acid using Titanium racks and Lead cathodes. Rhodium and Platinum plated Titanium is used for auxiliary anodes on bipolar racks to throw electroplated Copper, Nickel, and Chrome into low current density areas (recesses).
Click to expand...
Although almost any metal & graphite could be used in a sulfuric anodizing bath generally Aluminum(6063T6) is the best choice. Aluminum is much more efficient than lead or stainless by far. So if your doing a "hobby kit" anodizing using something other than aluminum will work but in an MFG operation aluminum is the way to go.
 
I anodize titanium framelock and liner lock scales. I use distilled water mixed with Borax. I have a DC power supply from Amazon that goes up to 120V. I place a plastic colander into a shiny metal pot (not sure what type of metal) to keep the titanium parts from touching the pot (cathode). I set a titanium rod across the top of the colander and hang titanium wire from this rod. I connect my alligator clip (anode) to this titanium rod. Has worked pretty well so far.
 
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