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Suggest the surface treatment for engine valves

Engine valves of two wheelers are generally grayish black with very good surface finish. The engine valve just after Liquid nitriding is not so good in appearance. How to achieve that shiny uniform grayish black finish.? Kindly note that I don't want the exact black color but grayish black color.

Maulik Savalia
plating shop employee - Mumbai, India
March 23, 2009

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Hi, Maulik. We have an article on line about Quench-Polish-Quench nitriding, and that may be what you need. But for a functional coating that the ultimate buyer never sees, I'd say it's whatever color it is for best performance. I would not impose an arbitrary standard regarding how dark it is.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 24, 2009

Try glass bead blasting them.

Guillermo Marrufo
Monterrey, NL, Mexico
March 25, 2009