A relatively high proportion of solvent has to be used. As this released, the film thickness will decrease, the aluminium powder particles become oriented and the desired metallic effect becomes evident. Self-curing acrylic resins as well as those requiring the use of a curing agent are organic suitable binders. As far as pigments are concerned, it is best to use organic pigments if a coloured metallic effect is required. These must be extremely light fast.
Incorporation of a suitable UV absorber in the binder will ensure light fastness. The only inorganic pigment suitable for this purpose, namely transparent red or yellow iron oxide, is relatively unproblematic. Paints formulated with this are extremely light fast, even if they do not always exhibit maximum sparkle. The paint's hiding power is due mainly to the aluminium pigment concentration. The lower this is, the greater will be the depth of colour and its purity.
Coarser particles, incidentally, result in greater colour saturation but usually cause a reduction in gloss. Aluminium powders with a medium particle size are the best to use.