No registration, no passwords; no pop-up ads -- just aloha, fun, & authoritative answers.
As an eBay Partner & Amazon Affiliate we receive compensation for qualifying purchases.
Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site
pub  Where the world gathers for
plating, anodizing, & finishing Q&As since 1989





-----

Black oxide fading on small parts





2000

We are doing black oxide on steel parts. After parts are blackened they have to go through a 10% acetic acid [on eBay or Amazon affil link] test.In order to be a success the black must not fade before 3 minutes.

The problem is:

When we blacken relatively big parts the test is a success. However, we seem to have a problem with small parts such as screws. The black fades after less than 1 minute.

What might cause the problem? How come only small parts give us a problem? Is there a way to make the black more resistant? ( not fade before 3 minutes)

veronica dewis
- Florida, USA



First of two simultaneous responses--

Veronica - There may be several factors contributing to your problem, but the most common are probably cleaning -are the screws cleaned sufficiently to allow a good coating to form? Also, is the operator overloading the basket or barrel and causing the bath temp to drop for too long of a time and decreasing the actual boil time that the parts need for the black oxide to form. A good rule of thumb is to have 1 lb. of parts for each gallon of tank solution. Hope this gets you started in your troubleshooting. Good Luck.

Dan Brewer
chemical process supplier - Gurnee, Illinois
2000



Second of two simultaneous responses-- 2000

Several possibilities.

It a very different steel.

It is a very different hardness.

You are probably barrel black oxiding them and it is taking part of the run time to warm up or, they are not having the same amount of contact with the solution possibly because of too much mass in a confined space or the holes are too small or partially peened closed and several other possibilities.

James Watts
- Navarre, Florida




(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully 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 might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact  -  Privacy Policy  -  ©1995-2024 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"