But isn’t this ‘type 2/type 3’ anodising just names for less thick and more thick taken from some US Army standard, and the process is less binary than they imply (as in some things are anodised better than others)?
Type 2, vs vs type 3 is not just a matter of thickness.
From Google below:
Type II anodizing creates a thinner oxide layer for moderate corrosion protection and decorative applications, often dyed vibrant colors, while Type III, or hardcoat anodizing, forms a significantly thicker, harder, and denser layer for superior wear and corrosion resistance in demanding industrial applications. The primary differences are the oxide layer’s thickness, hardness, durability, and suitability for dyeing.
Here’s a breakdown of their key differences:
Type II (Sulfuric or Decorative Anodizing)
Thickness: Produces a thinner oxide layer (typically 5-25 µm).
Appearance: Creates a porous surface ideal for dyeing to achieve a rich, metallic luster or vibrant colors.
Properties: Offers moderate corrosion and wear resistance.
Applications: Used for general commercial applications, decorative parts, and components requiring a good surface for paint adhesion.
Process: Often performed in a sulfuric acid bath at a higher temperature compared to Type III.
Type III (Hardcoat or Engineered Anodizing)
Thickness:
Generates a significantly thicker, denser oxide layer (often 25-100 µm or more).
Hardness:
Results in a harder, more abrasion-resistant surface (60-70 HRC).
Properties:
Provides excellent wear resistance, high durability, and superior corrosion protection.
Applications:
Suited for demanding environments in industries like aerospace, marine, and medical devices where heavy wear and tear are expected.
Process:
A specialized, low-temperature process that produces the thicker, harder coating.
I have 2 Skilhunt E3A in state blue and green colour body.
I use it about 3 years and usually carry it in little pocket of jeans trousers as backup light and state blue is like new, green one has a few light schratches, so green anodization can be a little weaker.