finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing.
    no popups, no spam
HomeFAQsSuggested
Books
Help
Wanteds
Advertise
on this site
FORUM
current topics
topic 6563

RED FINISH ON BLACK OXIDE


(2000)

I AM OPERATING A 200 GAL HOT BLACK OXIDE TANK AND CONTINUE TO EXPERIENCE A RED FLASH RUST ON THE SURFACE OF THE PART WHEN THE PARTS ARE MOVED FROM THE BLACK TANK TO THE RINSE TANK.THE PART ACTS AS A HEAT SINK AND WHEN DIPPED TO RINSE IT HAS A QUENCHING EFFECT. OPERATING TEMP IS 280-290F AND TRANSFER TIME IS ONLY SECONDS. WE ARE HAVING TO HAND RUB EACH PART TO REMOVE THIS REDDISH FINISH . WE HAVE CLEANED OUR TANKS BUT ARE STILL SEEING THIS SMUT! ANY SUGGESTIONS?

DAN MORPHEW
- COOKEVILLE,TN


(2000)

Got a suspicion...only that. Wonder if you use tap water to make up this bath? Tap water contains Chlorides, and you evaporate off a lot of water, I suspect, and I wonder if the Chlorides are causing this flash rusting?

Chloride has such a profound effect on all of metal finishing, that it always is a suspect, especially when corrosion is occurring.

Rudy Sedlak
Mountainview, California


(2000)

Dan -

It sounds like your parts are too hot, causing the iron freeze. Another cause could be that your tank needs rectifying - it has too much insoluble iron in it. Be sure to skim it every morning too - this will take out the floating iron when the bath is below it's operating temp.

Dan Brewer
chemical process supplier - Gurnee, Illinois



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Comment to THIS thread START a NEW threadView CURRENT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2018 finishing.com, Inc., Pine Beach, NJ   -   About finishing.com   -  Privacy Policy
How Google uses data when you visit this site.