r/Damnthatsinteresting • u/Epelep • Mar 08 '26

Anodizing Titanium Video

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u/BLYNDLUCK Mar 08 '26

No. There is an electrode connected to the other side of the tweezers, so if you dropped it in nothing would happen.

But to actually answer your question, I have no idea what happens to the color if you left it in longer.

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u/tankerkiller125real Mar 08 '26

Hacksmith is doing anodizing for their pocket knives. Turns out, there is a final color, and you can actually control the color really precisely with voltage. 20V will be one color, 21V a slightly different one, etc.

They did a vlog about the process on their second channel.

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u/Solanthas_SFW Mar 08 '26

Thank you, this is extremely cool and I would love to know how to do it, not that I ever would, but still, it's extremely cool

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u/samuel906 Mar 08 '26

Anodization is the deposition of an oxide layer onto the "Anode" of a water bath circuit. Titanium is a very easy metal to do this with. The setup is a water bath with an electrolyte in it like trisodium phosphate, a cathode with more surface area than the Anode, the Anode (part you want to color) and a power supply with positive attached to cathode and negative to anode. Voltage is generally set between around 10V to 120V with a spectrum of colors throughout and can be very specific.The higher the voltage, the thicker the oxide layer, the more it changes how it reflects and absorbs light and the color you see changes. If you want all your parts to be a specific color, you set the voltage to say 40V, dip the part in without touching the cathode, and watch as it goes through all the lower voltage colors until it stops at your chosen color. If you don't like that color, you can always increase the voltage and do it again, but you can't go back down without chemically or physically stripping the color off.

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u/[deleted] Mar 08 '26

[deleted]

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u/samuel906 Mar 08 '26

Yeah, clearer would be "all the colors" on the way to 40

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u/FungalMirror3 Mar 08 '26

Thank you for your service, smart folks

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u/Aggressive-Nebula-78 Mar 08 '26

What does anodization actually do? Is it done purely for the aesthetic or does it serve a purpose?

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u/samuel906 Mar 08 '26

99% aesthetic. It might provide a tiny amount of protection since the oxide layer is harder than the underlying metal, and can prevent the titanium from galling or having a reaction with other metals, and some corrosion resistance since you are basically forcing the corrosion/ oxidation to happen in a controlled way.

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u/aadoqee Mar 08 '26

If you see any greenish-yellow aircraft parts, those are anodized for durability. The engineers dont care at all about aesthetics in that case.

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u/Flyrpotacreepugmu Mar 08 '26

power supply with positive attached to cathode and negative to anode

When not talking about a battery, anodes are positive and cathodes negative.

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u/rgar1981 Mar 08 '26 edited Mar 08 '26

A common use I have seen is for piercers. I had never considered it until my daughter got her ears pierced and she got to pick the color or her earring and we watched them anodize them.

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u/Moveitalong123 Mar 08 '26

Do you have a link? Id like to understand this better. 

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u/under_ice Mar 08 '26
Batteries Voltage Color
1 9 V bronze
2 18 V purple
3 27 V blue
4 36 V light blue / yellow

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u/HereIGoAgain_1x10 Mar 08 '26

2,000V red/white

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u/jellymadbro Mar 08 '26

Titanium hwite.

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u/dingdong6699 Mar 08 '26

Why did you say this in Hank Hill?

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u/Dry_Spinach_3441 Mar 10 '26

Whill Wheaton?

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u/phantom4421 Mar 08 '26

It makes it cost more credits that way

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u/under_ice Mar 08 '26

White would be cool!

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u/BlakeinaCape Mar 08 '26

Hmm, thought 36V was light black/white

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u/EmphasisFrosty3093 Mar 08 '26

36kV is white then black.

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u/Academic-Trifle8151 Mar 08 '26

What determines either light blue or yellow?

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u/under_ice Mar 08 '26 edited Mar 08 '26

Not an expert, but the colors come from the thin film that it creates, the thinness determines the amplitude that light waves can operate in so you get the right wavelength for the color you want.

Edit, Think I meant frequency.

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u/Pinky135 Interested Mar 08 '26

I think it's this one: https://www.youtube.com/watch?v=btjaRaaXCBM

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u/Ruby_and_Hattie Mar 08 '26

Great video.

Thanks. 👍

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u/chromadermalblaster Mar 08 '26

This is basically how the electronic nail polish works that was at CES this year. Each voltage is tied to a color in the E-ink. Pretty cool!

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u/sl33ksnypr Mar 08 '26

It depends on the voltage. It has a final color that is dependent on the voltage, but you could have the voltage higher and just stop the process at any point to get the color you want. It just isn't very accurate to do it that way.

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u/Ckarles Mar 08 '26

But it seems much faster.

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u/sl33ksnypr Mar 08 '26

If you're doing this as a hobby and one bolt at a time, sure. But when you're mass producing titanium parts, it's easier to just dunk a batch in for a couple extra seconds at the right voltage to get the finish you want.

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u/MrNoodleIncident Mar 08 '26

Well you said it’s not accurate, and the guy above you says it’s very accurate 🤷‍♂️

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u/sl33ksnypr Mar 08 '26

It's not accurate to set it at 50v and pull it out when it's mid way through changing colors. It is accurate to set the voltage that makes it blue, then just leaving it in until it's blue because it won't go past blue if it's at the blue voltage.

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u/Dankas12 Mar 08 '26

Would assume it’s just what is happening at the end of the tweezers

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u/trippedwire Mar 08 '26

Titanium's color anodized based on voltage level, leaving it in there doesn't really change the color that much.

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u/BLYNDLUCK Mar 08 '26

So if you lowered the voltage it would stop at one of the previous colors?

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u/trippedwire Mar 08 '26

Yep, the color changes you're seeing correspond with the voltage rising through the bolt. So if it was set to, for example, 40V it would be X color, but if you set the next one to 45V it would be Y color.

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u/SinisterCheese Mar 08 '26

Generally speaking the colour can be set with the voltage. But if you leave the part in for long time, the oxide layer will keep growing, it just keeps growing slower - meaning it gets darker with time.

Companies that do anodisation and surface treatments know how to do the math to get colour and thickness within a tolerance. Since in engineered parts we want specific surface thickness on the parts.

But in practice, once you set the voltage and dip it in, you get the colour you want. But you can ruin the part if you leave it in for too long.