What are the points to note when formulating aluminium powder paints ?
A relatively high proportion of solvent has to be used. As this released, the film thickeness 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 organicsuitable 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 lightfast. Incorporation of a suitable UV absorber in the binder will ensure lightfastness. The only
inorganic pigmentsuitable for this purpose, namely transparent red or yellow iron oxide, is relatively unproblematical. Paints formulated with this are extremely lightfast, 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, incendentally, result in greater colour saturation but usually cause a reduction in gloss. Aluminium powders with a medium particlesize are the best to use.