RE. There is no need to heat the water. Some do. I think it speeds up the process, in fact if I remember right this along with other factors was one of the things the "Blue man" did when making his concoctions. I am not suggesting that is one of the factors that made him blue, just that I seem to remember he did it.

I think you'll find that the results of heating your water can do far more than that of speeding up the process. ie. heating your initial solution either close to OR at boiling promotes some serious chemical changes beyond that of pushing the reaction along. ie. the absence of oxygen and subsequent increase in conductivity as a result for example will promote the conversion of ionic silver into metallic form which ends-up being far more stable than any room temp solution(see: light sensitivity, oxidation etc). Similarly, the onset that a boiling solution somehow promotes amalgamation either during or after cooling is not based on good science and more importantly a non sequitur if/when current control limits are in place.

That being said, to my knowledge, I haven't read any references of the infamous blue man boiling his silver solutions. Which isn't to say that he never did as I'm sure I haven't read every single reference pertaining to his story. Though I really don't think it's accurate to try and associate argyria(indirectly or otherwise) with heating water while making colloidal silver tbh.

In closing I'd add that we have good reason to conclude that heat reduced colloidal silver is less susceptible to the chemistry changes that would promote argyria than with the ionic solutions. And I base this on the fact that it proves to be far more stable in terms of oxidation with less silver oxides than with he room temp solutions.

Hope this helps.