Where the
world gathers for metal finishing
Q&As since 1989


-----

60/40 Tin/Lead plates very slow if agitation is turned on

In our lab we are having significant problems with our tank. What we are noticing (to our surprise to say the least) is that with agitation with are getting low tin deposition, without agitation the tin is within spec. Of course there is no way we will run a tank witout agitation (this is bad practice) especially knowing that when we ran it before with agitation is worked fine (for two years). We have ran many analysis and the tin/lead concentrations check out, the rectifier works fine, we cleaned out the tank and bought new solution from our vendor and are still getting the afformentioned results. Please, anyone with insight on this issue provide some. Thank you.

Ayo osho
Materials Engineer - Baltimore, Maryland
2007

---

Are you absolutely sure that the parts are securely racked and you are not suffering make-and-break contact with the agitation on, Ayo?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

Thank you for your response. Our connection is fine as we have checked the current on the rack and on the piece the holds the part. More so, our (many) hull cell tests confirm what we are seeing in the bath. Adding more tin seemed like an easy solution but the amount that would need to be added would have to be much more than the limits we have adhered to for years.

Ayo osho
- Baltimore, Maryland
2007

---

2007

Tin Lead is not my long suite. You did not mention what kind of solution. If it is fluoborate and your agitation is too vigorous, then you are changing the stannic to stanous where it is of no good (unless I got that backwards), and this is especially detrimental if the agitaion is air (heaven forbid !) MOderate slow agitation is all that is needed. Too much will destroy the tin ingredient.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina