Vacuum metalising

From Wikipedia, the free encyclopedia

This article or section may contain original research or unverified claims. Please improve the article by adding references. See the talk page for details. (September 2007)

Vacuum Metalising is a process whereby a thin coating of metal can be applied to another material, textile / non-wovens / foil / paper, to achieve a high standard of finish at a low cost (compared to using solid metal or electroplating). This makes is particularly useful for disposable items, such as packaging, and therefore insulating inexpensive novelty items or where the cost of manufacture would be prohibitive by another means.

The Process

To metalise a product the process typically consists of three sub-processes, Basecoating, Metalising, then Topcoating. Though some plastics may require to be primed before they will accept the basecoat.

Basecoating

This is where the materials to be metalised are coated with a paint which prepares the surface by chemically attacking it, and as this paint has high electro-static properties it allows the metal to more easily adhere to the surface. Often for this paint to dry it has to be stoved as it's chemical properties do not allow it to dry in normal atmospheric conditions.

Metalising

For this process the materials are loaded onto a jig, along with the metal that is to be used to coat the material, typically aluminium. The jig is then placed into a vacuum chamber and a vacuum is drawn inside the chamber. When the vacuum has reached a sufficiently low pressure, the vacuum is "fired", this is where the aluminium is vapourised which coats the material. The chamber is then vented.

Topcoating

This is where a transparent paint is applied over the top of the metalised material to prevent scratching, or alternatively pigments can be added to achieve different looks, such as red pigment for a gold effect.