Tin plating turning dark

We are finding that Tin plated brass parts are shiny when received back from the processor, but turning greyish and dull over time. The coater is putting a copper base on the brass before the tin, but yet we constantly have this issue ? Any suggestions on what may cause it ?

Bob Baer
fastenter manufacturer - Wheeiling, Illinois, USA
October 23, 2009

October 28, 2009

This is a known problem of tin plating which is related to organics in the plating solution.

1. The plater has to use a post treatment after the plating. At least to dip in a slightly alkaline solution.

2. If the tin solution is very old and accumulated a lot of organics, sometimes you must replace it.

Sara Michaeli
Tel-Aviv-Yafo, Israel

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