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I need an idea on a good rust inhibitor for steel that is masked and plated alkaline zinc

Hi Folks,

Got a weird one. I am plating some low carbon steel pieces (short tubes) that get a rubber boot on one end. The piece is welded post plate so they don't want zinc there. My problem is that the pieces where the boot is masking are flash rusting after being non cyanide alkaline zinc and hex yellow chromate plated. I have tried with some success pre-oiling the pieces and applying the boot, then afterwards drying and oiling again. Some of the pretreatment chemistry is getting into the masked off part and making the surface very active. It is hit and miss but causing me a lot of rework.

Any ideas on a magic RP that won't contaminate my line but might withstand a little pretreatment chemistry?

Alkaline soak, HCl (40%), alkaline electro, HCl, caustic predip, alk zinc plate, chromate, dry. Counterflow rinsing between every step.

Trent Kaufman
electroplater - Galva, Illinois
May 26, 2011

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Hi Trent,

Maybe totally impractical, but can't you apply a hot melting wax and melt it away after plating?

Good luck,

Harry.

Harry van der Zanden
consultant - Tilburg, Netherlands
June 2, 2011

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Trent,

Would it at all be feasible to just run the parts through w/o the boot/masking and then strip back the area to be welded post plate?

Jimmy Canfield
- New Castle, Indiana, USA
June 3, 2011

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Trent,
I feel you have to master the masking technique!
I have once done this in India with great success, but the credit went to best masking techniques devoid of seepage.
Regards

T.K. Mohan
plating process supplier - Mumbai, India
June 14, 2011