Stainless Steel Anodizing

You cannot oxidize stainless steel because it is already oxidized (chromium oxide) and has a passive layer on the surface, which is generally corrosion-resistant.

What Is Anodizing?

It refers to the electrolytic process designed to increase natural oxide layer thickness on the metallic material surface parts. The essence of anodizing is to convert the metallic surface into a durable, decorative, corrosion-resistant anodic oxide finish.

Benefits Of Anodizing?

  • It offers aesthetics by offering a large number of gloss and color options and reducing color variations.
  • The exterior anodic oxides give great stability to ultraviolet rays and are repeatable.
  • It enhances the longevity of the material, thus offering long-term maintenance and operating savings.
Benefits Of Anodizing_
Reasons Why Anodizing Stainless Steel Not Recommended

Reasons Why Anodizing Stainless Steel Not Recommended

Technically, stainless steel is a natural excellent corrosion-resistant material. As such, it never corrodes but can only dissolve when subjected to an anodization process. In essence, the outer surface of stainless steel material will instead get gradually eaten away. Thus, it becomes difficult to attain the desired results because the surface material gets etched.

Alternative Process To Stainless Steel Anodizing

The ideal alternative process to consider for stainless steel in place of anodizing is referred to as passivation. It improves the corrosion resistance of this material by eliminating a wide range of ferrous contaminants such as free iron from surface material.

Passivating requires submerging stainless steel material into a chemical solution of nitric or citric acid for a particular period at given temperatures. It removes foreign impurities from the surface but not necessarily removing oxide scale or heat tint likely to be left behind by heat treating. However, for best results, you need to establish the specific grade suitable for passivation.

Alternative Process To Stainless Steel Anodizing
Effects Of Anodizing Stainless Steel

Effects Of Anodizing Stainless Steel

Ideally, the oxide layer often used in anodizing process tends to have an inverse effect on stainless steel material. Stainless steel is already oxidized and has a passive layer that makes it corrosion-resistant. In essence, it forms rust on the surface, and it means the effect offers more damage than good on stainless steel. Instead of anodizing stainless steel, it is advisable to consider conversion coating to make it more corrosion resistant. This process gives the material high strength and better corrosion resistance abilities in different environments.

Electrolytic Coloring Stainless Steel

Electrolytic coloring is a viable technique for producing a different range of colors available for various applications. The color effect is unique since this process hardly uses any kind of pigment or paint. Ordinarily, stainless steel surface has chromium oxide that makes it transparent.

However, electrolytic coloring is a vital technique for increasing its thickness without interfering with phenomena filter the light rays. The types of colors you get with this process in stainless steel include gold, bronze, green, purple, and red. Since electrolytic coloring barely has pigment, color is never degraded by UV rays and does not require maintenance.

Electrolytic Coloring Stainless Steel
Theoretical Stainless Steel Anodizing

Theoretical Stainless Steel Anodizing

Since electrolytic coloring barely has pigment, color is never degraded by UV rays and does not require maintenance.  Attaining the most efficient anodizing process on type 304 stainless steel, it would be ideal for applying electropolishing process before anodizing.

The most suitable electropolishing conditions are a current density of 0.55 A/cm² at 95°C for about 10 minutes. It provides the best smoothness and brightness. Substrate material that converts to oxide layer and sulfides in film are oxidized to soluble species in a positive cycle. In negative cycle, reduction of trivalent iron to divalent iron occurs, and hydrogen gas is evolved.

Features Of Brushed Stainless Steel Anodized Finish

The notable features include the following;

a) Lightweight – It is almost 1/3 weight of ordinary stainless steel material.

b) Scratch-resistant – No scratches and fingerprint marks can form on the surface material.

c) Eco-friendly – The process utilizes an environmental-friendly brightening approach to anodize the material.

d) Reflective – It exhibits a highly reflective appearance.

e) Needs minimal maintenance – Hardly requires intensive care to retain its shape.

Features Of Brushed Stainless Steel Anodized Finish

People Also Ask:

Can I Anodize Stainless Steel?


In the true sense of the world, you can never anodize stainless steel unless you use a hot caustic solution. Even so, you may consider a few alternatives to attain more or less similar results to what anodizing offers.

Why Anodizing Stainless Steel Causes Rust?

Because it has a natural corrosion-resistant layer made of chromium oxide. Therefore, this natural oxide layer tends to form rust on surface material of stainless steel when anodized.

Can You Anodize 316 Stainless Steel?


The anodizing process used in bathing materials would attack and dissolve 316 stainless steel.

Which Are The Alternative Surface Finish To Replace Stainless Steel Anodizing?
  • Heat coloring or flame anodizing
  • Black oxide
  • Painting
  • Hard coating
  • Passivation

More Resources:

Stainless Steel Vs Aluminum

Hydroforming Stainless Steel

What Is Anodizing

Metal Anodizing

Alloy Steel Vs Stainless Steel

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