Why not gelatin capped? Concern about it being less effective because of the capping?
Yes. The topical effectiveness of Colloidal Silver when capped with anything apart from glucose, corn syrup or cinnamon is currently unknown. It was previously thought that anything other than Ionic Silver Oxide or glucose/fructose/corn syrup Colloidal Silver would not be effective on bacteria when used topically.
After my experiments and the experiments in Africa, we now know that cinnamon-capped Colloidal Silver is effective, and for all intents and purposes, as effective as the others.
We know that gelatine-capping is highly effective at protecting the Colloidal Silver particles during the stomach transit, much more so than the other forms of capping. Until proven otherwise, I would therefore not use gelatine-capped Colloidal Silver externally, just as I would no longer use Ionic Silver Oxide internally.
We know how to make all variants, and it is therefore sensible to use the most effective version for the job in hand, until we know whether gelatine-capped Colloidal Silver is suitable for external (topical) use.
What about the silver borate possibility? Is that only an issue internally?
Any salt of silver, if adequately soluble, will work externally. Previous entries in the "Materia Medica" from the 1930's indicates that silver salts were in common use topically. [Don't get me on my soap-box about the days when doctors could actually do what they thought would benefit their patients, rather than increase the profits of the pharmaceutical industry]. I would suggest, however, that silver nitrate should not be used because of its' corrosive nature when in high concentration. The silver salts commonly-quoted in the Materia Medica were lactate, citrate and acetate. You could experiment with the borate; if so, let us know how you get on.