Here is a link to a key post by Jackson which, among other things, reminds me that I still have not found clear descriptions of preparing colloidal silver for receiver sheets, but what he says is tantalizing.
Here is the link
Here is an excerpt from Jackson:
The receiving paper doesn’t necessarily have to be fixed out photographic paper or film. Land discusses sodium sulphide and heavy metal salts like lead as silver precipitating nuclei on the receiving sheet, but colloidal silver may be preferable in the home darkroom. I haven’t found a clear, simple and practical description of Carey Lea’s dextrin method of preparing colloidal silver, in which a solution of silver nitrate is gradually added to a solution of sodium hydroxide and starch. The precipitate is then allowed to settle, and the liquid poured off, possibly after alcohol is added. If you could calculate the right quantities, you might to be able to mix a stock solution which could go directly into the Barnes and Johnston thickened monobath formula above, or a 1% gelatin solution for coating on paper. Example 1 in US patent 4888267 gives a similar but far more complex procedure, with completely unrealistic quantities.