Rieger Metallveredlung Blog – Layer thickness measurement - An essential quality factor
09.02.2022 - Blog

Chrome plating is not chromating

But what is actually the difference?

Again and again we receive inquiries about "chromating". However, chromating is often mistakenly equated with chrome plating. These are fundamentally different surface treatments. But what is the difference?

To explain that, let's start by briefly explaining what chrome actually is.

The name chrome is derived from the ancient Greek "chroma", which means color. It is one of the transition metals and has the chemical symbol "Cr". The metal is rarely found in nature in its natural form. Chromium is therefore usually mined in a bound form as the mineral chromite (chromium iron stone or chromium iron ore) in open pit mines or at shallow depths.

Chrome is a silvery white, corrosion and tarnish resistant metal with high hardness. It's not ferromagnetic. Chromium dissolves in hydrochloric acid and sulfuric acid over time, when the protective oxide layer is gone, with the formation of hydrogen. It can be used in a variety of ways in electroplating.

Now the difference between chrome plating and chromating.


The chromating is a conversion layer. Here, the chromium combines in ionogenic form as chromate with the respective base metal (e.g. zinc or aluminum). The chromate is formed with either hexavalent or trivalent chromium. Chromating in the hexavalent form (Cr6+) has fallen into disrepute and has almost completely disappeared from the market due to various regulations (old vehicle, electronic waste regulations, etc.).

Chrome plating:

On the other hand, there is galvanic chrome plating. Here, the chromium is deposited in metallic form. There is therefore no chromate or hexavalent or trivalent chromium! Chrome plating is divided into three types depending on the conditions in which the coating is used: bright chrome plating, hard chrome plating and black chrome plating. The area of application of the respective chrome plating is already evident from the name. In principle, almost all common metallic materials, including aluminum and its alloys, can be chrome-plated. Depending on the required conditions, the underlying layers are to be selected.

Rieger Metallveredlung offers the different chrome surfaces on a variety of different metals. The NICAL process is also used in preparation for the electroplating of aluminum and its alloys.

Of course, we do not offer chromating. As an alternative, we have special passivations here. And so we would like to conclude once again: Chrome plating is not just chromating!