the tin process after a while breaks down - the grain refiner - and stannous
turns into stannic - also current density decreases due to stannic tin and
breakdown of additive - deposit is not as pure and sufficient time is
required to plate sae thickness as originally. 

Atotech does have what they call a clarifier - it willpercipitate all the
stannic out - run a carbon on the bath - and ur off to the races once more.

need more info e-mail me at [log in to unmask]