Letter 2046

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I have recently sent some parts to be zinc plated with a yellow chromate conv. per qq-z-325 typeII class 3. After completion of this process my customer has refused these parts, saying that the finish is inconsistent. Can someone help me determine if this call-out for finish type, give the customer what he is looking for, or is this process going to give a inconsistent finish.

Thank You.

Mark Hurst
sheet metal. - Springfield, Oregon

It is not unusual for a chromated zinc part to meet the spec and not be acceptable to the customer.
Bright zinc will frequently have a mottled rainbow color. As you go to bronze and then olive drab, the effect lessens.

Larger flat sheets are hard to get to be uniform color because you are plating at different current densities, lower in the center and higher at the edges.. Brightness will vary and the chromate will take differently and definately show the effect of the heavier plat rate area.

Lots of customers think that the spec means jewelery quality rather than commercial.

If you want to lose a customer, point out that what you gave him meets the spec. since nothing is in contract form about this area, you are in a lose-lose situation.

James Watts - Fl

Mark, I note with interest that while your specification calls out for a functinal coating your customer rejects on a cosmetic appearance. Is the coating irridescent? this is normal. The acid test is does the part meet the salt fog requiement? Should the plater with for a darker chromate film the plater can add a SMALL amount of HCL tro the chromate tank. I have done this in the past to force a darker film. Some chromates are less prome to irridencence such as Hinkels Divercoat LR.

Regards

Jon Quirt
- Fridley, MN

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