Ghillie Blog

"Hard Anodizing" explained

After doing some research around the web on anodizing. I found out that some anodization processes can be done in your garage with plastic tub, sulphuric acid, distilled water, battery charger, some aluminum wire and a little knowledge.

Anodization is primarily used to toughen up the outer shell of the aluminum and is also an easy way to add color to your piece. What the process actually does is creates a aluminium hydroxide layer on the surface of the metal. After the process is complete the aluminum is no longer susceptible to nicks and scratches to the surfaces because the pores of the metal have tightened up creating a harder surface.

There are 3 types of Anodization

  • Type I -  is a specialist anodising using chromic or phosphoric acid instead of sulphuric acid,.
  • Type II - is the anodizing that can be done in a garage, using sulfuric acid and coloured dyes.
  • Type III -  is hard coat anodization, or Hard Anodizing. Requires a more controlled environment.

Type III or Hard anodizing is performed with a weaker solution of sulfuric acid, and a lower temperature acid bath. Normally for Type II anodising we have our acid bath around 60-70 degrees farenheit. The temperature often rises during the anodising process. For type III hard anodizing, the temperature must be at 35-40 degrees. The acid bath must be constantly mixed, otherwise a warm layer of acid will build up around the piece. The electric current will be much higher, perhaps 20 amps per sq foot. This requires bath mixing machines and cooling equipment.

The Result of Hard Anodizing is that you get a thicker stronger coating which is about 2-4 times stronger than the normal anodizing process. It's about as close as you can get to titanium while still using a easily machineable aluminum.

All of our Anodized Kettles use the Hard Anodization process, and I am proud to say that this is the most durable kettle to date.