Summary for tin plated copper black smear Discussion
Tin plated copper parts black smear/residue is the issue Miltos Gardikas raised for icemaker components after an acid-clean, alkaline degrease, and acid tin-plating sequence. He asked whether the process was wrong, whether tin naturally smears, and whether a food-grade lacquer or other protective finish was needed. In the discussion, the practical concern is that rubbing the plated surface with a towel or kitchen paper leaves black marks, which suggests either surface contamination, poor rinsing, or a plating condition that needs review rather than an expected property of good tin plate. The thread points readers toward checking the cleaning and rinsing stages, the tin bath chemistry, and whether a post-treatment or protective coating is appropriate for the intended food-contact use. The advice is framed as a process-quality problem, not something to assume is normal for tin plating.
April 7, 2021
Q. Greetings to everyone in this great forum. I have made searches to find the same subject post but with no success.
Except the Coffee makers problem with their tin plated(?) copper barrels and the peeling off .
I am Miltos Gardikas and working on a icemaker manufacturing Company. We do make TIN PLATING ON COPPER in some parts of the icemakers we produce as the European Community dictates.
We have the following procedure:
TANK 1: 20% H2SO4 and 80% water.
TANK 2: WATER
TANK 3: WATER
TANK 4: ELECTROLYTIC DE-GREASING IN ALKALINE SOLUTION (NaOH)
TANK 5: WATER
TANK 6: WATER
TANK 7: 20% H2SO4 and 80% water
TANK 8: WATER
TANK 9: TIN PLATING (ACID SOLUTION H2SO4)
TANK 10: WATER
My question is —
After process finishes THE PROBLEM is that when we use a towel or a kitchen paper and rub the surface, we get black smears on the towel or paper.
Can someone share his knowledge on this? Is this correct?
Is the process wrong?
Does Tin smear? Or leave residue?
If so, Is there a process like food grade lacquering to prevent this?
Where can I find more information?
Thank you very much for your effort in answering this.
MILTOS GARDIKAS
– LAMIA GREECE