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  for Metal Finishing since 1989
  

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hex chrome/laser marking/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. & laser marked S.S. instruments.Problem is if the hex Cr gets to low the laser marking 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.
1999

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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
1999