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in response to ur earlier e-mail  regarding above subject, u r definitely
right and to put it correctly - not clear on the issue.(  pun )

when the tin bath oxidizes for whatever reason and turns into stannic - the
grain refiner and wetters are what suspend the stannic colloid in solution -
oxidization of the solution is inevitable - that is the nature of tin. when
these tin colloids accumulate not only will they co-deposit but the
concentration of the colloids eventually accumulate causing an overall
deficiency of the process. filtration by itself will do nothing - the
colloids must be clarified from solution - coagulated - settled then if u
want to filter - u can - but - there will be enough coagualted stannic at the
bottom of the bath that u can actually scoop out with a shovel.if this is not
done periodically as a maitenance procedure - eventually
there will be enough suspended tin colloids and breakdown product - that it
just might cost u more to clean it up than replace it and wastetreat the
existing process. the clarifier that we manufacture ( ATOTECH CANADA ) is the
trick to the whole process.
the clarifier enables our customers to clean out their existing stannous
sulfate processes in about eight hours time - analyze the process - and it's
good as new!!
we have over 20,000 gallons of tin in operation in Canada - so we see samples
of these baths every week.

a stannous sulfate process is still less expensive to install, operate and
maintain. changing over from solder to tin is also beneficial in reducing
sludge in the tin stripper.  there will be enough of a deposit of  tin in a 6
to 7 minute period to act as a decent metallic etch resist. 


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