My first attempt at making colloidal silver

After rolling out some of the presumed fine silver made earlier, I saved some for making bands etc and still had two large strips which I thought I would try and use for making colloidal silver. I immersed two such strips in distilled water in a clean plastic container, and connected them to a 12v dc supply via a system of 6 12v bulbs, all in parallel. This is the system I use for etching and other related operations.

I left it running for several hours, with no visible light from the filament of the single bulb I had in the circuit (by unscrewing bulbs I can reduce the maximum current that can flow). But both slabs of silver darkened, rather considerably, and additionally I think there was a fine, faint fog of black silver particles in the water.

I tried a trick I found on the Internet, namely shining a simple laser pointer through the water; this plainly showed the path of the laser, giving some confidence that some at least of the silver was converting to colloidal form! I checked that the laser also showed such a beam when passed through colloidal silica solution, and no beam when passed through plain water.