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Ebonizing

Subject: black ebony
My company has a customer who is using a process called ebonizing. I can't find any data explaining this process or how it works. The process they showed me has a 10" diameter steel tube with a plate welded to the bottom with heating bands around it heated to a temperature of 800 degrees. The solution in the tank is sodium dichromate powder that goes into a liquid at 800 degrees. The level of solution is raised by adding more sodium dichromate to the pot. The 17-4 Stainless parts are dried, put in a small tray type rack and lowered into the pot. The process time is 40 min. The racks are then drained and set out to dry. The racks dry in about 20 minutes, and then are placed into a 200 degree tank to dissolve the dried sodium dichromate from the parts and rack. The parts will go through 3 more clear rinse tanks before being blown dry with air. The deposit is dull and black which is what they are looking for. We are thinking of adding this process to our hard chrome, gold and black chrome processes. I have been trying to learn more about this process. The company now doing it doesn't know where it came from or how it works other than what I have told you. They want my company to take this process into my plant and do it for them. Let me know if you or any of your techs might have any information on this process. I will need a MIL. Specification and an ASTM specification number.
Thank You,

Terry Stafford, Plant Manager

Terry Stafford
y&wtech - Memphis, Tennessee
2006