Anodizing titanium rings: Techniques and benefits

A few weeks ago I anodized the titanium guides on my NFC 661 HM, and I decided to put together a tutorial for anyone interested.

First of all, you need to know that titanium anodizing is a surface oxidation (titanium dioxide created by electrolysis). It is therefore a reversible operation: you only have to remove that thin oxide layer to get back to the original look. You can do it by sanding (though I would not recommend that on guides) or by polishing. It is not always straightforward, because while polishing a KL20 is doable, doing it on a KT4 is another matter, two frames from the Fuji guides range.
And since the coating comes off with polishing, rubbing the guides against something on a regular basis will have the same effect. So the finish can fade over time.

How do the colours work?

Anodizing works because titanium dioxide produces interference colours, meaning the colour depends on the thickness of the oxide layer. It is the high refractive index of titanium dioxide that makes this possible.
Varying the voltage used during electrolysis is enough to change the thickness of that oxide layer, and therefore change the colour.

So you can change the colour if you do not like it, by using a higher voltage. If you want a colour that sits at a lower voltage, however, you have to re-polish the part before starting the process again.

How to anodize a guide

Here is the equipment you need:

• sulfuric acid
• a container (glass or stainless steel)
• a stainless steel spoon if the container is glass
• flexible electrical wire with crocodile clips
• 9V batteries or, better still, a stabilized laboratory power supply (0-75V or 100V supplies are very costly, but perhaps you have access to that kind of tool at work?)
• titanium parts, in this case fishing rod guides

First, connect the "-" and "+" poles of the 9V batteries (or the power supply) to the stainless steel spoon (or the container) and to the titanium guide. If you have crocodile clips, it is easy.
I took a 9V battery clip, cut it and soldered it back onto 2 wires. It looks like this:

Then, in the container, I mix roughly half sulfuric acid and half water, and I dip in my stainless steel spoon, connected to the negative pole of the battery. If you use a stainless steel container, you connect the battery straight to the container.

Then the positive pole goes to my titanium guide (I had run out of guides for the photos, so this is a piece of titanium).

All that is left is to dip the guide into the acid solution, and the colour appears instantly. The anodizing does its job.
WARNING: do not dip the whole guide. The clip (crocodile or other) connected to the positive pole must not touch the acid solution, otherwise it goes sshhhrrriiiqqqqqq ...

Once dipped, rinse the part thoroughly under running water, dry it, and there you go!

To vary the voltage using 9V batteries, simply wire them in series (9, 18, 27, 36, and so on).

And that is it, done!
I admit I tried to get purple on my guides (75V) but with 9V batteries it is not great. I am sure a stabilized power supply would have given me a better result.
I ran several attempts and several polishing passes before finally settling on this purple-blue...

Editor's note: anodizing does not work on titanium tip-top guides, most likely because of a slightly different alloy.

Tutorial by J.C Claudel (Jazz Fishing Rods).

To choose the frame and the ceramic before you even think about colour, read our comparison of Alconite, SiC and Torzite. And if you damage a guide while handling it, the tutorial on replacing a guide covers the wrapping step by step.