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Zinc Chromate with a dull grayish appearance

I work for a distribution company that supply a manufacturer in the trucking industry. I have some u-bolts that are being manufactured out of 1018 steel and are being plated a .0005 thick zinc chromate. On occasion they come in with this horrible looking dull galvanized appearance. What would cause something like this? Is it the plating process contamination etc...or is this type of steel just that difficult to plate? I have been told that this is normal to see this, but in the last 10 years in the industrial supply industry I have never viewed plating this bad before. I have pictures, but I don't know how to get them posted on finishing.com to show. Can someone please provide some possible input on this for me?

Jennifer Sterchi
Industrial Supply - Madison, Tennessee, USA
2005

Ed. note: E-mail the pics to mooney@finishing.com and we'll post them on your letter, Jennifer.

Are the U-bolts barrel or rack plated? Sounds like the plater either loaded too heavy or ran out of brightener.

JEFF W LENTZ
- Lebanon, Pennsylvania
2005

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2005

I am assuming the one on the right is normal and the one on the left is not, I agree, it looks like there was a lack of brighteners in the plating bath these parts were plated on, other things could be problems in the cleaning sections of the line,or it could be bad chromate, One thing I do know is most platers won't let things that look like that out of there shop, This is a quality issue you must take up with your supplier, you're on your own with that.

Joe Avino
- Allegan, Michigan
2005

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If your supplier is providing some parts that look good, with some parts that don't look so good, I would say that he has a problem. Just tell him that the dull finish is not what you are paying for, and sent the parts back to him as rejects. If he can't fix the problem, then you need to find a better supplier. Dull, unattractive parts in zinc plate are not the norm.

Daryl Spindler, CEF
decorative nickel-chrome plating - Greenbrier, Tennessee
2005