Aloha, fun & authoritative answers -- no cost, no registration, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Where the
world gathers for metal finishing
Q&As since 1989

-----

Green hue on black anodize

2007

What is causing a green hue to appear on some black anodize parts?.The area is not uniform as it has apeared on different areas of the same part.The parts have been racked up identical to previous runs.
Anodizing parameters:1.5 amps per decimeter squared.
Anodizing temp 20 deg C.
Sanodol black MLW dye at 4.5 ph temp 60 deg C.
alloy 6061 fine bead blast finish
Anodizing time 1 hour
Seal with DI water boil for 1 hour ph6 for water seal.
What am I doing wrong?
Thanks,

Steve Power
Engineer - Nelson, New Zealand

Bead Blasting? Has the media been used on any other metal, like iron, copper, brass, etc? Bead blasting imbeds iron particles into the soft (Kleenex-like) aluminum metal, then when you anodize you also oxidize the imbedded metal. Iron usually comes out as red, but iron does form some green salts which may be forming in the seal. Always use blasting media that is 100% designated for aluminum.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2007

(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: