I have no problem with Argex silver. I am still using the same piece of silver I bought ages ago. Now, I have had 2 bottles of 100ppm go bad on me but that is almost a certainty that it was nothing to do with the silver, but more to do with my bottles having some slight contaminent or electrostatic thing or some such thing. I have made 3 litres of 320ppm and SO FAR it seems ok. I was not aware that 320 "may" not last as long, so I won't make any more of it in bulk at the moment. I will wait till I run my current batches down first and then convert more of my 100ppm naked to 320 gel capped.