The number of colloidal silver particles in a gram of the cream is beyond a humans ability to imagine. People recently coming into the forum need to understand that they don't need to multiply the tried and true values by 2, 4, 8, etc.
If you want to be a scientist with it then by all means, experiment. You have free will, can do what you want, and are responsible for your own actions, as with all.
It doesn't really matter what the medium is just as long as Colloidal Silver stays in tact and gets where it needs to be.
Using Colloidal Silver at higher concentrations than 20 ppm is really just a waste of silver and isn't really needed. 2-4 ppm kills germs. 20 ppm is already a 5x-10x overkill.
I read EVERYTHING in the forum before I tried ANY experimentation beyond what is recommended here.
Rubbing with a damp tissue I don't imagine would do as much as a bandage that is always wet with Colloidal Silver.
Sorry if this seems a but scattered... it's late.