Organic colouring

1. Characteristics and properties

The colouring process does not apply an additional coloured layer to an existing layer system, but the actual layer is additionally dyed. At Metoba, zinc is used as the coating. In practice, a galvanic zinc layer is deposited on the workpiece, which is then transparently chromated. This transparent chromate layer is then coloured with the organic colours in red, yellow, blue or green. Immediately after galvanizing and chromating, the workpieces are placed in a staining solution in which they must remain for a defined exposure time depending on the layer thickness, shade and intensity. During this time, the organic dyes are stored in the chromate layer. In addition to the properties of the deposited zinc layer, such as cathodic corrosion protection on steel, the coating system also has other advantageous properties, such as the decorative aspect and UV stability of the ink layers produced. As this is a solid-coloured coating system, even minor mechanical damage does not damage the decorative effect. Furthermore, the dimensional stability of the layer remains unchanged.

2. Benefits and areas of application

Organic colouring is primarily used as a decorative finish, but is also used in conjunction with the technical properties of the layers to improve corrosion protection. When applied to steels, the organic colouring of zinc layers opens up new avenues in terms of decorative corrosion protection in conjunction with guaranteed chromium (VI) freedom. An additional benefit is the possibility of colour identification. For example, it is possible to galvanize two identical screws made of different steel alloys with different tensile strengths, to additionally color one of the screws, and thus to install the right screws in the right places during the assembly of assemblies in a way that prevents confusion.

3. Basic material

Steels of all kinds are particularly suitable as the base material. After suitable pretreatment, however, non-ferrous metals and their alloys as well as aluminium and zinc die-cast can also be organically coloured.

4. Required delivery condition

The goods provided must be largely metallically bright. Residual oils or residual impurities must be removable with conventional aqueous alkaline degreasers. Oils containing silicone, alkali/alkaline earth and high-pressure additives must be avoided at all costs.

5. Pre-treatment

Components are galvanized and chromated before colouring.