Friday, September 5, 2008

Anodising Aluminium at Home - Part 2

I have been through this process numerous times and have not experienced success as yet, but will still record the steps I am making. I am sure I will find the solution to my problem soon and as I am describing my journey of the anodising project, I think the failures should be noted also.

Please refer to Part 1 for the safety precautions and bath preparations.

The piece of aluminium to be anodised needs to have all the work completed first e.g. cut, shaped, hammered, formed, drilled, sanded and polished if desired. In my experiment I am using a scrap piece of aluminium which has been drilled and sanded.

I recommend having a timer for all the steps, I couldn't do without mine ($5.00 from the supermarket).


I'm going to fast track to the actual anodising step for a moment. The set up includes a strip of aluminium which sits across the top of the bath container. I have drilled a hole in the strip. Using 1.6mm aluminium wire I have doubled it up, squeezed it together with pliers and fitted it very tightly into the hole. The wire is long enough to prepare the other end in the same way and tightly wedged into the aluminium piece to be anodised so that the piece is completely submerged in the acid bath. I keep it attached in this way to complete the whole process starting with -

Wire in Aluminium piece to be Anodised

1. Degrease - submerge in the jar of detergent for 5 to 15 minutes

Degreasing aluminium

2. Place in rinse bath for 2 minutes

Rinse bath of Distilled Water

3. Immerse in Caustic bath for 1 - 3 minutes

Soaking in Caustic Soda bath

4. Rinse under a running tap for 3 - 5 minutes

5. Place in Nitric Bath for 2-3 minutes to ensure the grey colour has been removed

Soak in Nitric Acid Bath

6. Place in rinse bath of clean distilled water for 2 minutes then rinse under running tap for 3-5 minutes

7. Anodising Bath - Using a piece of roofing lead, I've cleaned it with steel wool first, placed it on the left side of the bath with 2/3rds immersed in the acid/distilled water solution. I'v placed the aluminium bar with the attached piece of aluminium to be anodised across the top of the bath. The aluminium piece should be completely submerged and a distance away from the lead. I'm using a 12V battery charger, the black connector is attached to the cathode with is the lead. The red connector is attached to the anode wihich is the aluminium bar.

A piece of Roofing Lead as the Cathode

Aluminium piece across the bath which I have now changed with a more substantial Aluminium Bar, the Aluminium piece to be Anodised I have now fixed through a hole in the Aluminium Bar

The ampmeter on the battery should sit between .5 and 2 amps. Many bubbles form around the lead cathode and fizzes.

The Ampmeter on the Battery Charger

The Battery Charger

Now this is where I am going wrong. The amps drop back to zero which indicates I no longer have contact. I'm having difficulty fixing the aluminium wire to both the bar and the piece to be anodised sufficiently to result in a tight connection, hence the electrical charge fails to travel down the bar, through the wire and into my work piece.

As soon as I have overcome this problem, I will continue the process. Of course if any of my readers can help me out here, I'd be very much appreciated!

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