Letter 3049

ANODISING ALUMINIUM 

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I HAVE TRIED ANODISING ALUMINIUM,WITHOUT VERY GOOD RESULTS I HAVE BEEN GETING INFORMATION ON THE PROCESS FROM YOUR LETTERS AND THE INTERNET.

I AM USING SULFURIC ACID, 1130,SG, AND .160 AMPS PER SQUARE INCH. TO GET BLACK I HAVE FOUND I NEED TO PROCESS IT FOR FOUR HOURS TO GET A BUILD UP TO HOLD THE DYE,THE INSTRUCTIONS SAY 40 - 60 MIN.I AM USING PRINTER INK (HP) AND I AM USING PHOSPHORIC ACID AS A CLEANING AGENT. I ARIVE AT THE AMPS BY THE FOLLOWING EG.2.25X24=54X.160=8.64AMPS OR SHOULD IT BE- 2.25X24X2=108X.160=17.28 AMPS.

HOPE YOU CAN TELL ME WHERE IM GOING WRONG, SOME ONE H E L P.

RICHARD LANE
- NEW ZEALAND

"I HAVE BEEN GETING INFORMATION ON THE PROCESS FROM YOUR LETTERS AND THE INTERNET" -- You are getting your information from the wrong place. You have to read books and journals if you want to work safely, intelligently, with high quality standards, and with proper respect for the environment.

The basic difference between a book and an Internet page is that somebody spends two years writing a book, and 5 minutes writing an Internet page.

Your second formula is correct assuming the article has two sides. I suppose phosphoric acid could do some light cleaning for you, but it's no substitute for an alkaline cleaner. Sorry, my 5 minutes is up...

 
Ted Mooney - finishing.com - Brick, NJ

WELL HERE IS WHAT U NEED FOR THE ANODISING.THIS IS IN STEPS.

• 1. DEGREASING (TRICLOROETHLENE WILL DO BUT i SUPPOSE IT HAS BEEN BANNED )
• 2.SOAK CLEANING(CAUSTIC CLEANING 5MIN 50C)
• 3.WATER RINSING
• 4.ACID CLEANING(CHRIMIC ACID15-20Gm/LIT+SODIUM FLOURIDE2-3Gm/LIT)
• 5.RINSING
• 6.CAUSTIC ETCHING(2-5MIN AT 60C)
• 7.RINSING
• 8.DESMUT(NITRIC ACID40% AT ROOM TEMP)
• 9.ANODISING(10-15% SUPHURIC ACID WITH ALUMINIUM CATHODESFOR 45-60 MINUTES AT 30-45 AMPS/SQ FT)
• 10.RINSE
• 11.DYE IF NEEDED
• 12. SEAL IN BOILING WATER FOR 30-40 MIN.

i AM SURE IT WILL DO THE JOB IF NOT U CAN ALWAYS COME BACK.BEST LUCK.

KHAWAR
- ISLAMABAD.PAKISTAN

I've had very good results anodizing small aluminum parts from web page information, but not overnight. You have to get a feel for it. This site and others like it are very rich in information, but you have to sort it out for yourself. You won't get much safety information from the web, either. :(

Joe Davisson
St. Louis, MO

Anodizing time required =[ 400 x desired film thickness, um]/ current density,A/m2

Lim Heng Kam
- Mantin, Negeri Sembilan, Malaysia

Trichloroethylene hasn't been banned just yet. I found a page with it for $40.50 for 5 Gallons of a cleaner base on the solvent. I've avoided using these sovents what with all that stray UV from the welder, I love to breath myself.

John Heritage
- Merseyside

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