[Svartalfiar]

But he actually grinds up silver coins himself and stirs it up into some kind of shake. So it might not count to the purists here. Grinding up old US coins is not giving him pure silver.

Grinding up old coins, no matter their silver content, isn't going to work. Colloidal silver is atomic level - there's no way he's grinding it up into particles that small.

[TigersEye]

Colloid (the root of 'colloidal') is a scientific term pertinent to both chemistry and physics. The processing and use of colloids has thousands of industrial applications that spin off into many more thousands of uses for the products created.

It can be difficult for the average person to understand scientific and industrial terms like colloid. It's far beyond the 18th century technologies of grinding grains or mineral ores into fine powders.