The authoritative public forum
  for Metal Finishing since 1989
  

  -----

"Red iron bleed out" in black oxiding

We are currently black oxiding drill bits we are processing these bits in a 285 degree caustic blackening solution and dipped in a light oil after the blackening process is complete. We are experiencing a red iron bleed out as they sit for a day or two. We thought we may be burning them but they look fine for the most part after they come out of the solutions, (no acid is used.) Having them bleed out like this is not working with there shrink packaging because of the mess it is developing inside the package. I was hoping that someone may have an answer to what is going on and how to eliminate the problem for good.

Richard Miller
metal finishing - Portland, Oregon, USA
2004

---

Assuming your black oxide is working well, giving you a good black color, I'd guess you are not rinsing well enough, or you are packaging them with some moisture. Another possibility is contamination of your rust proofing oil. Pack some up using new oil, also pack some up which your KNOW were dry, and with new oil and you should see where the problem lies.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2004

---

I just would like to add to my request for information on the red bleed out problem we are experiencing on the drill bits. Our company has been in the black oxide business in the Portland area since 1936. Our tanks are cleaned every weekend and our chemicals that we use are one of the best out there on the market. our operating temp. for our 6'black oxiding tank is kept at 285-287 degrees. Our company is a job shop which handles a wide varity of different materials which 99 percent of those materials we process we have no trouble with. Except when it comes to these drill bits. After our processing is complete they are shipped out of the state back to the manufacture. As you can see this has been very trying and puzzling for us. Any information will be appreciated!

Richard Miller
metal finishing - Portland, Oregon, USA
2004

TRY "PACIFICATION" . I'M TALKING ABOUT THE SAME PROCESS THAT IS USED ON STAINLESS STEEL [Ed. note: 'passivation']. AFTER THIS PROCESS AN A GOOD RINSE GO RIGHT TO OXIDE BATH .

BRIAN HOLCOMBE
BLACK HAWK M. T. - HOSCHTON, GA, USA
2005

Hello, You mentioned typical"Pacification" of Stainless Steel, can you described this process please?.

John R Hayes
- Sydney, NSW, Australia
2006

---

I don't think there is any such process as 'pacification'; I believe it was just a typo or misspelling of passivation. This is a process to surface enrich stainless steel with chromium and/or (depending on who you believe) provide a durable chrome oxide skin, with the object of deterring surface rust. It can be done with citric acid, nitric acid, or an electropolishing process. If you patiently search the site you will find dozens of responses about it. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2006