Flake Aluminium: The first flake grade is Bright aluminum. Bright aluminum usually passes 120 mesh (nominal mesh size 120-200) and is very fluffy and leafing mass. They are used as a fuel for many purposes and to obtain silver effects. The second flake grade is called “flitter” which means flake powders of a larger mesh size than bright aluminum. It is sold as “fine”, “middle” and “coarse” flake/flitter. Some people think that using flitter larger mesh variations are allowed. Sometimes this might be true but corresponding to the correct mesh size often makes the critical difference. As a rule of thumb, fine flitter is: 80-120 mesh, middle flitter is: 30-80 mesh and coarse flitter is 10-30 mesh.
Aluminium is a neurotoxin that alters the function of the blood-brain barrier. Additionally, small particles that are airborne act as tiny razors when they come in contact with lung or eye tissue, and a dust mask and goggles should be worn at all times when working with aluminum powder. Mixtures containing nitrates and aluminum powder are prone to heating up spontaneously and may ignite, especially when wet. This is caused by the reduction of the nitrate by aluminum, forming amides. These very basic compounds react further with aluminum powder in a very exothermic reaction that can cause spontaneous ignition. An ammonia smell is often produced in this reaction. Adding 1 to 2% boric acid to compositions containing nitrates and aluminum is common practice and will often prevent spontaneous ignition.