Being a painter for 20 years I think that I can answer your question.

Steve is partially correct concerning the composition of the flakes. I just got through putting some House of Color "Ultra Mini Flake" in the clear on my HotSpot. These are plastic, being made from Mylar. The "pigment" in silver/aluminum paint is indeed aluminum flakes. The coarseness of the sparkles is controlled by how fine the aluminum particles are ground. The coarser alunimum paints actually contain both plastic and aluminum flakes.

Remember in the 70's and 80's when all of the silver finishes turned dull and flaked off? This was caused by the aluminum "pigment" in the paint oxidizing. Oxidation took place because the aluminum in the paint was exposed to moisture and most importantly---air. I say "pigment" in this post but there really is no pigment in aluminum paint. Primarily just aluminum flakes and a binder to adhere the paint to the surface. The cure for the oxidation problem was to clear coat the silver paint---problem solved. No more oxidation---no more flaking.

I have never had a silver/aluminum finish affect the range on my radios. Kevin