five nines is about as good as it gets, and that is very expensive. i use 99.9+ and have done just fine with it. four nines is all anyone concerned really needs to go with, and six nines is unheard of in my experience.

>- It seems really hard to get 99.9999% pure wire. Even Alfa Aesar only sells 99.999%!

>- Surely 99.999% is ok?

This is five-nines and with todays technology, this is the best that you can get.

99.99 % or four-nines should be sufficient.

you can get 5 nine thats .99999 not 99.999 there is one place in new jersey that carries it. its surepure metals, in florham park, new jersey. I purchased 1 foot of rods at one quarter inch thick. I paid 180.00 for it. good price it will last a lifetime. no impurities. in it, lead mercury etc. just pure stuff. makes cuts etc heal faster, it seems to me. i tried all purities, and 5 nine is definately the best.