PAM 172 Tantalium case set research

[kilowattore]

Tantalium vs titanium

Daydreaming of a 172. Can it be done?

As most of you know, in 2003 Panerai released a few models whose case was made of Tantalium, the most appealing to me being the PAM 172 produced in 300 pieces only for F series.

"tantalum (redirected from Tantalium)
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Related to Tantalium: tantalum, tantalum oxide, Tantalum capacitor
tan·ta·lum  (tan't?-l?m)
n. Symbol Ta
A very hard, dense, gray metallic element that occurs chiefly in columbite-tantalite and is exceptionally resistant to chemical attack below 150°C. It is used to make electrolytic capacitors for portable electronic and computing devices; superalloys for aircraft, missile, and nuclear reactor parts; filaments; and surgical instruments. Atomic number 73; atomic weight 180.948; melting point 3,017°C; boiling point 5,458°C; specific gravity 16.4; valence 2, 3, 4, 5."

Gen pics:

Notice how the case seem to change color in the pics?
Visually tantalium looks pretty similar to titanium, but it has a darker shade of gray and tends to appear lighter or darker depending how the lights hit it.
Besides, unlike titanium, when high-polished it looks closer to stainless steel.

The reasons above made it very difficult to obtain a proper looking case set to be used in a rep or an homage. Afaik only Davidsen released a PAM 172 tantalium version and he worked his way through the color issues using titanium for the darker brushed parts and stainless steel for the lighter colored polished parts.
The result is nice, but not very close to the gen reference. Overall the rep case set looks too light colored but still good.

I know the difference is subtle, but you know how these things go...
I wanted a 172, but I wanted the case to have the right color so I started researching and found a few interesting processes, mostly based on a combination of reaction to chemicals and heat.
I then sourced a couple of titanium case sets to use for experimentation

These are the results of the first method I tried. They look nice to me so if I'm lucky I could call it a day already, in any case I'm posting to keep track of my results and to hopefully hear your thoughts and/or advice though I know this is not the most sought after Panerai.

Please don't mind the details such as dial, hands, CG and crown. The watch has been built with spares only to test the durability of the case finish.

Work done on the bezel:

I experimented on the titanium bezel to see how close to SS I can make it look. I have a few different polishing compounds and I know from my experience that they may affect metal color when used. 
Bezel has been first sanded then hand polished. It still needs work as I did not remove completely the brushed finish before polishing, but this is just a preliminary experiment to check how its color compares to the SS CG after my polishing job so it will do for now. 
I used sand paper in increasing grits from 1500 to 5000, then polished it with three different dialux polishing compounds. 
Next time I will start with 1000 or 800 grit in order to obtain a perfectly smooth surface before polishing. I expect no need for coarser grits since titanium is softer than steel thus easier to scratch.

Work done on the midcase:

First thing I did was cleaning the case with soap and water, then I rebrushed it to get a crisp finish,
Next it was thoroughly degreased with vinegar (or the likes). You need to remove all grease from the case. After you cleaned it, you better use gloves to touch it. 
For safety reasons gloves are required anyway for next step. 

The watch was then submerged in boiling water (circa 300 ml) and then a tablespoon of oxyclean powder was added (any other cleaning powder containing sodium perclorate you can find in your country should work). Let it stay there for 30-45 minutes then clean it and carefully dry it with a paper.
After a few cycles I obtained a color close to my goal, but the chemical reaction created some funny color spots (bronze, purple, blue shades) that had to be removed. I found the best way to do it is using a steel wheel on a dremel, but you need to be extra careful and make very light passes with the wheel or you will remove the patina and will have to start again. Done

Notes for next try:

The brushing is not as defined as I'd like it and the color is not perfectly uniform. Case must get out of the "bath" darker than desired, in order to allow a final brushing step, or the initial brushing must be coarser.

Now, let's see some pics.
In order for to you to understand better the color difference, I photographed another titanium cased watch I built from parts (call this the poor man's 040 ;)).

So, I would really appreciate your opinions on this. Do you think it looks ok already or I should better try and find another way around?

Thanks for reading anyway

 

[Tribal]

For me it looks nice.Congrats

Gesendet von meinem MI 4S mit Tapatalk

[GBOGH]

Looking good. Could maybe treat it some more for slightly darker grey on the case

[TerraZ]

Nice start! You got closer than I think what was possible.

I would really love to see a great tantalium-like rep case as well, but it's really hard to do. From some angles the gen it looks really dark, from other angles the case looks shiny and bright.