Anodising aluminium black may be easier than you think. With a few commonly found materials from your local hardware store, you can transform aluminium from a dull grey to a brilliant and impressive black. Anodising makes the outer surface of aluminium much stronger and prevents oxidisation. It is also the only way to permanently colour aluminium.
Clean the piece of aluminium you wish to anodise as thoroughly as possible. Use dish washing liquid and water for this task. After washing, degrease the aluminium using some degreasing cleaner.
Desmut the piece of aluminium by submerging it in desmut liquid for about 2 minutes. Use one of the polythene tubs for this step. Warming the solution to about 60 degrees Celsius will improve the desmut results.
Mix one part sulphuric acid with one part distilled water in the other tub. Add the water first, then slowly add the acid. You should mix enough to fully submerge the piece you wish to anodise.
Attach the negative cathode from the power supply to an aluminium plate. Submerge the plate into the acid solution.
Connect the positive lead from the power supply to the aluminium piece you want to anodise using a length of aluminium wire. Place the piece of aluminium into the acid bath solution.
Turn on the power supply to 12 volts DC at two amps. Monitor the cathodes for bubbles forming in the acid solution. This will tell you that current is flowing.
Remove the piece of aluminium when you notice no more bubbles forming on the cathodes.
Mix 4 tbsp of black anodising dye with 2 quarts of distilled water. Submerse the piece of aluminium in the dye solution for 15 minutes. Heating the dye solution to around 37.8 degrees Celsius will help to make the dye adhere better.
Remove the piece of aluminium from the dye solution. Seal the aluminum's surface by boiling it in pure distilled water for about 30 minutes. Remove the item from the water after the 30 minutes have elapsed.
Changing the amount of time the aluminium sits in both the acid bath and the dye as well as changing temperatures will enable you to slightly modify the depth of colour.
Always wear appropriate eye, hand, skin and body protection when anodising and working with acid. Always dispose of acids and dyes in the appropriate manner; contact your local waste management company for details. Keep some baking soda handy to use to neutralise any spilt acid.
Tips and warnings
- Changing the amount of time the aluminium sits in both the acid bath and the dye as well as changing temperatures will enable you to slightly modify the depth of colour.
- Always wear appropriate eye, hand, skin and body protection when anodising and working with acid.
- Always dispose of acids and dyes in the appropriate manner; contact your local waste management company for details.
- Keep some baking soda handy to use to neutralise any spilt acid.
Things you need
- 2 polythene tubs, 10 gallons each
- Dish washing liquid
- Desmut liquid
- Sulphuric acid
- Distilled water
- DC power supply
- Aluminium sheet and welding wire
- Aluminium plate (cathode)
- 2 gallon pot
- Black anodising dye
- Safety gear
- Baking soda