NEW YORK (
) -- For those expecting an explosive piece of investigative journalism, tracing some sinister link between silver and weapons of mass destruction, my apologies. When it comes to "germ warfare," silver's role is entirely a defensive one.
I have looked at several of the companies using silver as an anti-microbial agent, and I have learned a little more about the biological aspects of this application.
The first point to make about this technology is that I had (erroneously) referred to this previously as "anti-bacterial" technology, directly implying that it was only effective against bacteria. As I quickly discovered, silver has much broader "anti-microbial" properties -- meaning that it kills not only bacteria, but also molds and fungi.
The next point to make here is that this anti-microbial effect is produced through the release of silver ions, the active agent which kills microorganisms. These ions can be released in different ways (and different rates), depending on the precise composition of the anti-microbial substance.
In the case of silver, the three main categories of such substances are ionic additives, salts and metals. The primary difference among these substances is the rate at which they release silver ions, and (conversely) the length of time that these substances can maintain their anti-microbial effect. Thus, the type of silver anti-microbial treatment used will depend on the nature of the product being devised.
In the case of "silver body-washes," and other single-use applications, the silver ions would be delivered through ionic additives, which release these ions at the greatest rate/speed -- and are completely soluble in water. On the other hand, with anti-microbial treatments which are intended to be durable (such as clothing or upholstery with these anti-microbial additives), it is important that the ions be released much more gradually, so that the anti-microbial effect lasts for as long as practically possible. For these applications, the metals-based products are most appropriate.
In between are the salt-based anti-microbial products, which are less water-soluble, and have a slower release of ions than ionic additives and a greater duration of effect.
More specifically, I was introduced to a Swiss company,
, which "manufactures high-performance textile effects for the most demanding functionalities." To explain this in greater detail, HeiQ manufactures "microcomposite" silver- additives which can be used to add anti-microbial properties not only to textiles, but also to medical devices and plastic coatings.