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Anodizing titanium to green color -- Q&A's

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Q. I've recently taken to try to anodize some titanium.

I tried first with TSP, from a box, probably not very pure. It nearly destroyed the Ti. I tried this at 0.1N and 1.0N concentrations. It corroded the Titanium and visibly pitted the parts.

I then tried with Sodium Bicarbonate. It worked MUCH better. I was able to get blue, pink, light green, gold and pink at different voltages using a series of 11 Volt battery packs.

Unfortunately this setup was not able to get me the vivid Emerald green I was going for even at 90, 100 and 110 volts. These all went to a magenta pink with little difference between them. I did this on grade 5 titanium.

My goal is to anodize an entire Titanium bike frame (grade 9 3/2.5) to emerald green.

Can anyone give any insights as to what I may need to do to achieve this result? I may be getting access to a variable transformer so I am not limited to 11V steps.

I will also be receiving a sample of tubing in 3/2.5 to test on before doing the actual bike frame in a big plastic tub or 55 gallon drum. I am using titanium wire for the cathode and a piece of stainless steel for the anode.

Brandon Wasser
Hobbyist/ chemist - Montana
September 6, 2023

⇩ Related postings, oldest first ⇩

Q. I have done anodizing on titanium. The blues are easy to achieve. I have been experimenting and trying to get greens but have not yet been successful. Perhaps some one could suggest the correct solution and voltage to help me out.


Todd Huehn
plating - Blaine, Minnesota

A. It takes very nearly 200 volts to get green. This is serious voltage. Make sure that you have an isolation transformer in the circuit and you have quick blow fuses of the appropriate amperage on the output side. A volt or two will make a fairly significant difference in the color for whatever solution that you use, so experiment.

James Watts
- Navarre, Florida

A. My experience with Titanium anodizing showed that you get different colours with the same voltage, on different titanium alloys. Therefore one cannot exactly say at what voltage you'll get what colour unless he has experience with the same alloy. Also, different colours will be obtained depending on what has been done to your part -- e.g., embossing will badly affect the colour which you'll get.

Mark Camilleri
- Malta

"Corrosion Behavior of Anodized Titanium Nanotube Used in Implant"

on AbeBooks

or Amazon

(affil links)

A. Color anodize on titanium is fairly straight forward. What is not is obtaining a coating that is biocompatible. Contrary to popular belief the solution and cell play a role. I for one am fearful that shops jumping into the market will kill it by offering any finish produced as implantable. This is not a paperclip or nut and bolt market.

Jon Quirt
- Fridley, Minnesota

Parts is parts.

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey


Q. When you anodise titanium, does this then increase its corrosion resistance? How stable is the blue oxide layer in an acidic environment?


Steve Van Smaalen
steel - Port Kembla, NSW Australia

A. Hi Steve. In general, metal oxide coatings do not increase acid resistance because oxides tend to dissolve into acids quicker than raw metals. I don't think titanium is any different than most metals in this regard, but if anyone feels differently, please let me know :-)


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Green anodizing of titanium sword

Q. I have been trying to acquire some titanium (which is remarkably hard to buy) to create a katana to anodize green (it just seems like a interesting thing, I'm in 9th grade (15 years old) with my parents permission, but I can't seem to find the right voltage. My friend let me try his but all I got was dark blue sort of stuff.

Nathan Figueroa
Student - NYC, New York

A. In USA you can buy small quantities of titanium from Reactive metals studio. They sell anodizing equipment and booklet too. Good luck!

Goran Budija
- Zagreb,Croatia

A. To get a green colour on titanium is hard - it is the last colour you get with anodising as you raise the voltage before the oxide layer goes grey, and with some alloys you don't get a green at all. It usually takes about 70-90 volts DC, which can give you a nasty shock, so wear rubber rubber gloves [on eBay or Amazon (adv.)] and avoid anything that could cause a short circuit. However, if you are fully aware of the safety precautions, then try it, with adult help. You need to make the titanium the anode and use a piece of stainless steel as the cathode. For the electrolyte I use dilute sodium or ammonium sulphate [on eBay or Amazon (adv.)] or phosphate solution. I estimate that a strength of about 1 gram per 100 ml would be enough. If it is too concentrated, a large current will flow and you can get sparking as you lower the sword into the electrolyte - quite dramatic, but not good for the oxide colours! The best way to get the colour you want is to gradually increase the voltage while taking the metal out to check it. Sometimes each colour takes a couple of minutes to develop. The sequence of colours from 5 volts up is brown, purple, dark blue (20 V), light blue, yellow (40 V), gold, pink (50 V), magenta (pinky purple), emerald green (70 V), apple green, grey. Good luck !

Jeremy Wyatt
- Epsom, Surrey, England

Ed. note: To emphasize Mr. Wyatt's cautions, this sounds like a good idea for a science project that can be done under the supervision of your science teacher. Not all adults (in fact few adults) are trained in safely working with electricity, and these voltages are definitely not innocuous.

Flared area of titanium tube turns black instead of anodizing

Q. I am trying to anodize pieces of 7/8" diameter 1/2" long 6-4 Ti tubing. The green colour is problematic when I anodize flared sections of the tube. The non-flared areas seem to colour just fine. The parts are high polished, and surface roughness doesn't seem to matter when I try obtaining the green colour, it just looks "blackodized" in the flared areas. I've tried various solutions, but to no avail. I think it is being caused simply by the shape of the part. Does this make sense to anyone? Any help would be appreciated.

Jeff Swayze
Hole Joy! - Kelowna, B.C. Canada

"Jewelry Concepts and Technology"
by Oppi Untracht

on AbeBooks

or Amazon

(affil links)

A. Hi Jeff. I don't believe that the problem stems from the shape. Perhaps the tooling that does the flaring involves heat or oils that are spoiling the effort. I would scrub the flared area with powdered pumice and detergent and see if it makes a difference. Maybe see if it's possible to bend that tube by hand, and if the stretching alone has caused some metallurgical dislocation that causes blackening at the bend. Good luck.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Can't seem to green anodize titanium in sulfuric acid

Q. I want the ratio of mixing acid and the voltage to be applied. I am using sulfuric acid for colouring of titanium, and lead sheet as anode. So please tell me what I have to do for bringing green colour to titanium.

- Puduvai, Tamilnadu, India
January 23, 2008

A. Hi, cousin Arivazhagan.
Jeremy has told us earlier on what voltage to apply, and that he uses dilute sodium or ammonium sulphate or phosphate solution as the electrolyte. I think the answer to your question then is to use dilute sodium or ammonium sulphate or phosphate solution at the voltage he suggests, rather than to ask what voltage and what ratio to use for sulfuric acid :-)

Good luck!

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. Hi,
My name is Prashant R.Pillai.
I am in research for colouring of titanium. I have successfully managed to colour titanium in bronze, blue and yellow . After many trials I am not able to get green colour even at 110, 120 & 130 Volts.
So please do suggest the best medium and voltage to get this colour.

Prashant Pillai
student - Pune, Maharashtra& India
March 31, 2009

? Hi cousin Prashant. Please try your best to frame your question in terms of the answers already offered on this page preceding your question. For example, are you using the alloys and the processing solutions previously described? Thanks!


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. Please help~
One of our medical products (titanium washer) is required to be anodized in color green and gold. The gold one works fine, but the green ones all failed.
Below is the letter from our supplier.
We are told

"as the crystallites broke out along turning grooves a possible cause can be a high temperature treatment were titanium changes its crystallite structure between £\ and £] phase."

Can someone help to explain what could be the root cause?
Any suggestion to solve the defect like this?

The parts have been activated prior to the coloring in a pretreatment process, POLINOX TB 100, to remove the Ti-oxide layer.
Then the parts have been colored according to the order information.
After this process we have observed an inhomogeneous color on the surface on parts.
We have stopped the production and analyzed the situation.
We have found that the activation process removed non homogeneously material along circular grooves.
The result is shown in the pictures and is visible as non homogeneous surface structure.

Thank you in advance~

Alice Chao
Manufacturer - Taiwan
August 13, 2009

Ed. note: Sorry Alice, we have no pictures from you -- please re-send.

⇦ (tip: readers like to learn from your experiences; they seem more disposed to respond to your actual situation than to abstract questions   smiley face

Q. Dear All,
Can anybody tell me, why there is so many problem created for obtaining green colour in titanium anodising.


Rahul Ghagare
- Mumbai, Maharashtra, India
December 4, 2014

A. Hi Rahul. As you see, we appended your inquiry to a thread on the subject, which should offer some helpful info. Thread 1265 also addresses this -- see the postings on that thread from Jon Quirt and Anna Berkovich. Good luck!


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

A. Green is very difficult to obtain. I start by buffing the material to a very shiny state, then removing all buffing compound with acetone [on eBay or Amazon (adv.)], alcohol and ammonia.

When it is very very shiny and surgically clean, I suspend in distilled water. I do not touch with hands anymore -- use medical disposable gloves from thereon.

You'll need to etch it next. I use Multietch at about 150 °F with a fish tank air bubbler for agitation. I then etch in this solution (make sure it's fresh, can't reuse it more than once or twice). I let it etch for about 7 seconds, then quickly remove and immerse in distilled water, then wipe it down with a lint free cloth (etching too long removes the finish).

After it's clean again (remember, no touching) -- I reuse the ammonia; here it goes back in distilled water.

To get green I find I need somewhere between 95 and 120 volts DC depending on alloy and other factors (such as preparation). I use 7% phosphoric acid in distilled water. I refrigerate this and even place acid bath in a container of ice so it stays cold.

Put in the piece, use voltage like I said, don't let any part of the electric lead get wet (this can be tricky and require creation of creative fixtures.)

Remove it, it should be green. Start with low end of voltage range and increase until you get the green you want. If you prepare the items for this process methodically, same way every time, you should be able to achieve similar results on similar alloys.

Christopher Susie
- Baltimore, Maryland USA

A. Wow! That was a detailed description, Christopher, thanks!

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey

A. Problem of achieving green colour is in the solution. At higher voltage you must keep high diffusion. I recommend solution of 0.1 H3PO4 or any NaH2PO4, Na2HPO4 works best, and easily achieves green at about 120 V. By addition of Fluoride salts you may drop down voltage into 90 V. But remember to keep the low amount of acid around 0.1-0.2M.

Marcin Klomski
M&K - Gdańsk Poland
December 21, 2015

thumbs up signHi Marcin. Thanks for the great specifics!


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. Hi, I work at a medical device company and we have a product that we two-tone anodize "lime" with a "tan" cap. Our usual process that has worked for the last X years is the following:

1. Machine Complete
2. Wet Blast to prepare surface of product
3. Wipe product down with alcohol
5. Load parts on fixture
6. Anodize process:
a. alkaline clean (hot)
b. running rinse
c. etching
6.1 Load air tight cap to the top of the medical device
d. double running rise
e. anodize LIME (highest voltage)
f. triple water rinse
g. DI water rinse (hot)
h. dry parts off
7. un-rack part and remove caps
8. load parts back onto fixture
9. Anodize process 6 e-h and anodize TAN
10. un-rack parts and move on to next op

**The TAN should not appear on the LIME as it's a lower voltage than the LIME even though we don't mask the LIME area before we anodize TAN**

So, our main problem that is arising is the TAN color showing up on the LIME section EVEN BEFORE anodizing TAN. It used to be blotches that would appear under the lime giving it a brown hue, but now its creating what look more like scratches that are densely populated all in the same area.

We anodize another product all lime (not two-tone) and the lime anodizes fine on that product.

So, we believe the cap is causing an issue for two-tone. However, we anodize another product two-tone ROSE and TAN and have not seen any issues using the caps on that product.

My questions are:
1. Do you have any advice on two-tone anodizing? i.e masking techniques, air tight seals, etc.
2. Do you have any advice on preclean/ pre finishing before the anodize process. (We changed from wet blast to dry blast and it did not effect the coloring, both were splotchy)
3. Sometimes they come out fine with the EXACT same parameters and then if you repeat, it comes out splotchy. Has anyone experienced anodize not being consistent?

Any advice is appreciated. Thank you.

Cass Ort
- Nashville, Tennessee, USA
March 13, 2019

A. We do 2-tone (blue/grey) anodize on Titanium as a proprietary special process, and the biggest advice I have is to really think through your masking- engineer it well, and don't skimp on the construction. In our case, this meant machining clamp-on masking fixtures with Viton o-rings that then compress tightly against the part and don't allow leakage. Each part has to be literally BOLTED into the masking fixture, and then the whole thing gets tossed in the tank.The high pressure exerted by the fixture on the sealing surface is critical to get a nice clean line between the two different colored regions.

Rachel Mackintosh
- Greenfield, Vermont

⇦ (tip: readers like to learn from your experiences; they seem more disposed to respond to your actual situation than to abstract questions   smiley face

-- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. How To achieve Green Colour In titanium Grade 2 in medical Implants ? Please help

Raghav Vohra
Job - Delhi, India
June 26, 2021

Q. Hi.
Before anodizing titanium (Grade 2, Grade 4) at voltages above 20V, we use electrochemical etching.
The etching bath consists of: chromium trioxide (CrO3), hydrofluoric acid and water. For etching, we use the parameters: U = 10-12V, t = 5-10s. The same process is also used before green anodizing titanium alloy (Ti6Al4V).

Without this etching, there is a problem with getting the right color for the anodized object (especially for turquoise and green). Do you have any idea what can be substituted for the chromium trioxide in the bath used? What could be an alternative to the electrochemical etching bath?

Piotr Stasiewicz
- Lewickie, Poland
November 14, 2022

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