Foils are made differently according to what type they are. 

They all start with a transparent polyester film. This will normally be 12 micron, but can be thicker. 

The film is then coated with each layer using a gravure coating method. (Basically a cylinder which picks up minute quantities of the coating and applies a thin layer all over the film.) 

Generally the visible layers are sandwiched between a release coating and an adhesive coating. (see diagram)

Typical Make up of a metallic foil

Magnified photo of a foil viewed from the side

These "various" layers combine to produce a "variable" product. Each layer is coated within a tolerance. 

The end result is that once manufactured the foil has to be tested in order to asses that it meets the tolerance. Then it is  given a batch number which will identify it for future checking. (normally on the id label)

It is expected that from time to time a difference will be detected between batches. This is normal.

The additional processes are dependant upon the type of foil being manufactured. (see below)

Metallic's :Between the release and adhesive layers is a coloured lacquer (i.e. orange to produce a gold), and aluminium (applied by a vacuum metaliser).

Holographics :In addition to the above process, the release coating has a very fine embossing pressed into it. When light is then directed onto the foil the embossing refracts the light, causing a holographic effect.

Special Effects : In addition to the metallic process, the lacquer coating can be made of a partial or a pattern coating. Alternatively there could be more than one coating producing a multi-colour foil.

Pearls : These use a thicker lacquer coating made of pearlescent pigments, but have no metalised layer. The result is a semi-transparent foil.

Transparent :These use either a plain transparent lacquer or the lacquer can be embossed to produce a transparent Holographic foil. This has very fine amounts of aluminium coated on to reflect the pattern

Pigments : Whilst still being sandwiched between  release and adhesive layers, there is only a pigment layer, no coloured lacquer. Generally the release layer is applied in the colour coating to reduce coating applications. The only variations between pigment foils, being the thickness of pigment to achieve opacity, and a clear lacquer to produce a gloss finish. Sometimes a foil may have no adhesive coating, or this coating is mixed in with the pigment. These foils are generally for thermoplastics.



Woodgrains :These are multi-coated pigment foils. The coatings are patterned to resemble woodgrains.