REPOST: The Chemistry of Socks

What Am I? 19 was socks with a silver additive (emphatically not  nanoparticle silver )  to cut down on odour.  I thought it might be appropriate to repost this blog post from February 4th  2009, originally on Endless Possibilities v2.0 over on Nature Network. I never did copy the archive over when I moved…never mind!).


I bought socks as Christmas presents. I know, I’ve become ‘that person’ who gives socks at Christmas. It is still playing on my conscience a little: what an unimaginative gift. Yet, at the time, I felt I was investing in a kitsch Christmas dream. As it happens, the whole process of purchasing said socks was extremely irritating. It was hard to find socks that didn’t come laced with ‘antimicrobial technology’. Some of this antimicrobial (which is the-science-bit talk for ‘stops your socks smelling’)technology involves some quite interesting chemistry. Other examples of this antimicrobial technology involves quite a bit of plain bad science, in the name of marketing of course.I worked rather hard at Christmas to avoid socks with ‘Purista in them (ETA: Other silver products are available.. This was because I didn’t know what it was. I was, after reading many packets, quite well versed in the supposed benefits of this technology, but I still didn’t know what it was. It turns out that Purista is based on a polymer, polyhexamethylene biguanidine that is both a fungicide and a microbiocide. Sounds great, just what you might want in socks. Or would you? Is this an example of clever marketing playing on the public’s fear of germs, bugs, bacteria and the like? This technology is attached to the fibers of the sock by hydrogen and strong electrostatic bonds and acts to kill bacteria by puncturing their cell walls. Most unpleasant for the bacteria. In theory, those strong bonds that attach the molecules to the sock fibers should be able to endure normal wear and wash cycles. I bet you never knew that socks had so much technology in them, did you?

It all gets a little more complicated when we look at what else might be in our socks. Silver for example. Silver is known to have an antibacterial effect, indeed, many metals are. The problem with silver is that it is often made into micro- or nano- sized particles. There are concerns over nanoparticulate silver’s toxicity, and the impact that such substances have in the environment once the garments containing them are washed.

You will be relieved to know that despite many studies probing the effects of silver nanoparticles in socks and the environment, we can be reassured that silver is ‘a naturally occurring element’ and socks treated with silver are ‘chemical free’. Of course, if its natural and chemical free, it must be OK.  These are the claims of one such website peddling silver in socks.</p> <p>In the end I bought the socks that were free of antimicrobial stuff, preferring the ones made of natural (in the sense of being derived from plants or animals) fibers. Merino wool I believe. Snuggly.

Refs:

I found some information on Purista in a review article: Holme,I. Coloration Technology,2007, Vol 123, Iss 2, pg59 – 73, DOI: 10.1111/j.1478-4408.2007.00064.x

Information on the environmental issues surround silver can be found in an editorial and referenced articlees: Lubick, N. Environmental Science and Technology, 2008, DOI: 10.1021/es8026314