No passwords, No popups, No cost, No AI:
we earn from 'affiliate link' purchases, making the site possible

Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

finishing.com -- The Home Page of the Finishing Industry

  The authoritative public forum
  for Metal Finishing since 1989

-----

Black spots on electro-gold colored anodized aluminum

Q. Dear adviser,
I am working on Al 6063 alloy. I have a titanium salt based electro-gold color tank, where I maintain the following parameters:
Gold-salt= 4-5g/l, H2SO4=15-17 g/l, Temperature= 57-60 °C, required time= 3.0-5.30 min. Recently I'm facing a problem that showing a black spot on gold color surface after Ni-based cold sealing. It appeared between the flat profile when it is wrapped and 3-4 days later. Also appears a white powdery layer when two flat surface profile attached/bundled by wrapping paper. Please advise me how can I solve it.

Kamruddin Kamru
Nikki thai Aluminium Ind.Ltd.bd - Dhaka, Bangladesh
November 16, 2018

(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: