Aluminium flakes give coatings and inks their metallic brilliance. The first choice is between leafing and non-leafing grades.
Leafing
Leafing flakes are treated, typically with stearic acid, so they float to the surface of the wet film and overlap like leaves. The result is a bright, chrome-like, highly reflective finish with good barrier properties. Leafing films cannot be overcoated with a clear and are sensitive to rubbing.
Non-leafing
Non-leafing flakes are distributed through the film. They can be combined with coloured pigments for metallic colours and can be protected by a clearcoat, which is why they dominate automotive-style and industrial metallic finishes.
Other choices
- Particle size: fine flakes give a smooth, silky look; coarse flakes sparkle
- Flake shape: "silver dollar" flakes are brighter than cornflake types
- Vacuum-metallised pigments: ultra-thin flakes give mirror effects in inks
- Water-based systems: use stabilised grades to avoid gassing
