Re: how does club soda remove stains?

Club soda (or soda water, as it is called in Australia), it pretty simple 
stuff.  It is just plain water with large amounts of carbon dioxide (CO2) 
dissolved in it.  It's the carbon dioxide that makes it (and all other 
fizzy drinks) fizzy.

In terms of removing stains, I suspect that the carbon dioxide is being 
converted to carbonic acid (H2CO3).  It is probably the carbonic acid that 
is acting on the stains.

You could probably use any carbonised soft drink to remove stains, as long 
as the drink itself doesn't stain the fabric...

I know this isn't a very complete answer, but I hope it's helped a little.

Jonathan Feldman
University of Western Sydney, Nepean
feldj@rocketmail.com