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hex chrome/lasermarking/passivation

I'm wondering about passivation of laser marking. Is it really needed if so what is the best method? I also use sodium dichromate to passivate is there a method or simple formula to maintain the hex chrome level? Our passivation system is used mainly for 400series S.S. & lasermarked S.S. instruments.Problem is if the hex Cr gets to low the lasermarking comes off and/or the 400 S.S. gets attacked. Any help at all would be very helpful. thanks Tim Connors

tim connors
warsaw ind.

Yes, you must analyze your passivation solution. Without spending too much time looking it up, I would analyze for acid, and hexavalent chrome. Based on what we have learned from other letters about passivation, I would also make sure that I was not dragging oil into the bath along with the parts or racks, and I might even analyze for trivalent chrome.

Tom Pullizzi
Falls Township, Pennsylvania

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