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Adventures in Anodising

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Avro:
I have been messing around with anodising this last few weeks and thought I would share my early results. It was with some trepidation that I embarked on the adventure. You Tube videos make it look so easy and the results perfect; I knew it would not be like that! My apologies to anyone who actually knows what they are doing where anodising is concerned! That said I am happy to make mistakes and have a bit of fun with the process. Here is my set set-up in the kitchen, or rather what I now call 'The Lab' (you can probably guess that I am not married!!):
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...and here are the first victims, Suntour SCII pedal cages form a set of pedals I am restoring for my Laserlite:
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They have been stripped in a caustic soda solution. I have sanded then with 400 grit, then 800. It is a balancing act I think, how much metal to remove in order to get a reasonable finish whilst maintaining detail. The stamping on the ends is not very deep. After they were sanded I dipped them again to clean them and to remove the more stubborn areas of anodising, in particular where the screws have been. From now on it is rubber glove time. After this they are dipped in a nitric acid solution to to clean off any impurities from the surface of the metal.

Now we come to first major mistake. You have to suspend the item in the anodising tank by aluminium wire. I had read that where the wire touches the item to be anodised there may be left an area where the anodising has not taken. I wanted to avoid this so I just hooked the wire and hung the parts that way ERROR. All that happened was that the the electical connection was no where near good enough and the wire just spark eroded away and the cages fell to the bottom of the tank after a few minutes.

Take two and I wrapped the wire around to give a better connection. As it turns out you need a VERY tight connection in order for the process to work. I ended up crimping the wire tight in the end to avoid the spark eroding, I was thinking sparks and hydrogen are not a great mix. I future I will use nuts and bolts to make the connection, if any one has some M5 or M6 aluminium nuts and bolts I would be grateful for a few.

Anyway, here are the cages in the tank all wired up and bubbling away:
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After an hour I took them out and rinsed them off. They do not look a lot different at this stage, just the metal has a dull lustre to it. On the hob I had a pan with a solution of black dye at 50 degrees centigrade. Plop in go the cages for 20 minutes or so (I have recorded all the timings at every stage so that I can tweek things as I, hopefully, advance). The temperature is kept constant, too cold and more time is needed, too hot and you risk sealing the anodised layer too early:
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When the colour looks about right the cages are dumped into a pan of near boiling water for 1/2 hour or so to seal the dye in.
Here are the results of my very first experiment in anodising:
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Not too shabby although the picture flatters them somewhat. They are a bit patchy in colour but on the whole I was encouraged. I will redo them next week when I have some time off work.

Andyboy77:
Nice one Peter! Thanks for sharing this!   :daumenhoch:

Ady:
Thats amazing results mate..
Nice bit of kit looks expensive but rewarding to do.
You must be single or an understanding missus .
My other half would kill me..
Top work mate..
Cannot wait for the next episode.. fistblump

Midschoolfool:
Boiling up the awesome sauce :D

Nice job man.

Avro:
I have done a little more work on this. I have had a set of Dia Compe MX900 calipers, with centralisers, for some time; originally for my Raleigh Aero Pro. The Aero Pro has now moved on but the calipers are perfect for my Laserlite. However they are raw and no evidence of any anodising what-so-ever. For the Laserlite they have to be black. So into The Lab!

The brake arms have been stripped and sanded with 800 grit, then 1200 then 2000. I then gave them a light polish. Same process as before. The first results were poor, patchy and uneven so I did not seal them and simply dumped them back in the caustic soda solution. I gave them another sanding, careful to try and achieve a consistent finish, back in the etch, back in the nitric acid, rinse, and start again.

It is difficult to calculate the amps required, I am using the fixed amps method, as you need to know the surface area of the parts. I decided to up the amps over what I used for the cages and see what happens.

Here are the brake arms prior to dipping:
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...and after:
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I have not polished these yet but I am thrilled! I think they are going to be good enough to use, I am really rather chuffed.
Hopefully there will be more adventures in anodising to come.

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