Recommendation? Hard anodizing

[Spenser Johnson]

Happy Sunday BF!

Looking for recommendations on somebody to re-do the type iii, not type ii. Type iii, hard black anodize on an aluminum scale I have. 5 years ago I sold my last knife to fund a new business venture and just last week I tracked down that exact knife. I’m now in the process of slowing bringing it back to factory new condition.

Any recommendations are appreciated!

 

[Mk-211]

There's plenty of videos, that show you how to DIY it, if you can't find anyone.

 

[Spenser Johnson]

FOUND

 

[Mr.Wizard]

There's plenty of videos, that show you how to DIY it, if you can't find anyone.

I do not believe that will not yield "Type III" anodizing. According to https://www.precisioncoating.com/hardcoat-anodizing-type-iii/ you need either higher voltage or AC current.

Conventional Type III aluminum anodizing uses a high voltage process (up to 100V) to create the oxide layer. The aluminum object itself serves as the positive electrode (or anode, from which the term “anodizing” originates) in the process. The formation of the oxide film take place by the migration of Al3+ ions away from the metal towards the electrolyte interface, while simultaneously O2- ions from the electrolyte move in the opposite directions.

The acid solution used in hard anodizing is concentrated at around 200g/liter. The voltage used starts at 25V DC and increases to 60-100V as the process continues.

Conventional Type III coatings can be sealed by hydrothermal or precipitation means, or left unsealed. Choice of seal depends on the object’s intended purpose and use.

An alternative Hard Coat method that achieves superior performance properties is the Sanford Low Voltage rectification process where an AC current overlays DC current and leads to lower resistance at the anode surface. This produces a more uniform coating with a number of performance improvements. Sanford Low Voltage Processes include: PLUS, QUANTUM, and MICRALOX.

Further the solution is cooled rather than heated, e.g. https://caswellplating.com/hardcoat-type-iii-anodizing-system.html

To achieve the small pore size, the anodize bath must be chilled down to 37-40 def F with the use of a chiller (not included).

From https://aerospacemetalsllc.com/what-is-hardcoat-anodizing/

The sulfuric acid is cooled to near freezing, and a current of upwardly of 100 volts is applied. Current densities usually range from 24-40 amps per square foot (ASF). The current is applied until the desired oxide thickness is achieved; it can then be colored or sealed.

The temperatures are controlled, typically between 28-32º F and in some instances, higher temperatures. The process forms an abrasion-resistant oxide film that is extremely hard. Thick coatings require more process control and are produced in a refrigerated tank near the freezing point of water with higher voltages than the thinner layers.

And from https://www.anoplate.com/news-and-events/how-hard-is-hardcoat-anodize/

Hard anodize, also known as hardcoat, is typically done with:

1. sulfuric acid with or without additives
2. 25-40 F near freezing chilled electrolyte
3. uniform and strong agitation to remove heat from parts during anodizing
4. higher current and voltage than conventional anodize.

 

[Spenser Johnson]

I do not believe that will not yield "Type III" anodizing. According to https://www.precisioncoating.com/hardcoat-anodizing-type-iii/ you need either higher voltage or AC current.



Further the solution is cooled rather than heated, e.g. https://caswellplating.com/hardcoat-type-iii-anodizing-system.html


From https://aerospacemetalsllc.com/what-is-hardcoat-anodizing/


And from https://www.anoplate.com/news-and-events/how-hard-is-hardcoat-anodize/

It most definitely will not yield type iii but I still did appreciate the recommendation