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Wednesday, January 21, 2015

Anodizing - part 4

Partial success… or partial failure?

This has been a very long day, made even more stressful by handling gallons and gallons of acids and other toxic substances. In the end however, it was well worth the effort, even though the part did not come out as intended.

I learned a lot today, and I was glad to have solved most of the logistical issues in the past few days, using a bucket of tap water, or it would have been really challenging trying not to spill anything.

But let’s start at the beginning…

This morning I mixed all the acids, dyes, and other nasty chemicals in their respective buckets, then warmed each one up to its nominal temperature. It turned out to be a very good thing to do, because a few unexpected things occurred. 

The PID box started heating up, after running the heater in all 6 buckets. I had the feeling this could happen, but so far it hadn’t been an issue in the limited testing I had done. I should have cut some slots in the box anyway, and now I will, but for the time being I just opened the box, and ran it that way.

The last thing I did yesterday, was to lengthen the thermocouple cables by splicing in a couple of feet of 22 gauge wire. I did this to gain some flexibility with the placement of the PID enclosure on the table. This had a strange side effect though, causing it to read 30 to 50℉ higher. Apparently the thermocouples are calibrated with a certain wire length, and making the leads longer screwed things up. 

In order to get 140℉, I’d have to set the PID to 170℉, and 197℉ was reached using 245℉. Not a really big deal, but another variable to have to juggle. 

Heating up the orange dye

Bringing the sulphuric acid up to temperature

To begin the process, I took one of the rejected brake brackets off the shelf, hooked it up to a titanium wire, and dunked it in the 130℉ degreaser for 5 minutes. I should have probably have spent some time cleaning it up beforehand, but I thought the hot degreaser might just be enough.

Degreasing the part

After 3 minutes in the de-smut solution at 100℉, I moved on to the actual anodizing at 71℉.

Anodizing has started, evidenced by the bubbles on the lead plate.

Given the amount of surface of the part, the online anodizing calculator suggested 2 amps for 2 hours.

This makes it easy

I had a bit of trouble getting a steady current, until I figured out that I needed a better connection with the titanium wire, after that it worked great.

I don't know about the volts, but the amps are right where I need them to be.

Two hours later I took the part out of the sulphuric acid, rinsed it thoroughly in distilled water, dunked it in the 140℉ golden orange dye, and three minutes later, the part looked like a million bucks.

This part looks amazing already

This color is so nice, I couldn't stop staring at the it.

Man, it looked awesome!

I was ecstatic at the color, that is until I took the bracket out of the 197℉ sealer. The part was in the sealer for 30 minutes, but after coming out and air drying, instead of looking great, it just looked a little dull.

I took a microfiber cloth, and tried to polish the bracket, but the color started rubbing off!

That wasn’t supposed to happen!

I’m not really sure what caused it. I know that the part was not clean before the degrease immersion, so perhaps this was the reason, but I won’t be sure until test #2.

Anyhow… on with the pictures of the semi-successful, or semi-failed anodized part.

The micro cloth rubbed the color off


  1. Hi Marco,

    Enjoying your build and blog - very motivational and inspiring - so please keep up the good work.

    You might enjoy this (rather long) Youtube video - note how thorough he is on the cleaning and rinsing part: http://youtu.be/BtYHcsq7s5A

    Best of luck,
    Henrik (Building LZ in Denmark)

    1. Thanks Henrik,

      Tom is actually one of the guys I follow on YouTube, and I did watch his video just before anodizing. I can't believe I skipped that step, I don’t know what I was thinking! Maybe the chemical fumes had started to affect me already.

      I plan on running more tests in the next few days until to see if I can improve the results, and post what worked and what didn't on the blog.

      Ciao, Marco.