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  • Sulfuric Acid: The Chemical for Anodising Aluminium

    Sulfuric acid or Sulphuric acid? How to spell it?

    It is my understanding that the traditional spelling of "Sulphuric" is with the "ph". However, it now appears that the internationally accepted spelling is now "Sulfuric" with a letter "F" in the middle. I will try to stick to using the letter F, but may slip occasionally, because, being English, I naturally type Sulphuric.

    The Chemical formula for Sulfuric Acid

    Sulfuric Acid is H2SO4.

    About Sulfuric Acid

    Sulfuric Acid is a strong mineral acid that can easily be dissolved in water. When adding acid to water, the mixture will become quite hot, and must be left to cool before attempting to anodise. In the old days sulfuric acid was known as "Oil of Vitriol" and was probably discovered around the 8th Century. Aside from water, sulphuric acid is perhaps the most commonly manufactured chemical in the world!

    Sulfuric acid has many uses. Normally we find it inside lead-acid batteries in solution with water. It's main industrial use is in the production of phosphoric acid. It is also used in papermaking, as a catalyst during production of Nylon, a variety of uses, which, of course, includes anodsing.

    Sulfuric acid is very nasty stuff, and can be neutralised with an alkali, such as sodium bicarbonate (found in baking powder).

    Where to buy sulfuric Acid

    Sulfuric acid is not easy to buy. In our society anything that could be used for evil purposes is generally hard to buy! Although commonly found in car batteries, most retailers are not allowed to sell the acid itself to you.

    There are a number of online shops that do sell bottles of 98% solution.

    November 2007: Please note the above suggestion no longer works. It is very difficult to find anybody selling the chemicals these days. It might be worth talking to these guys http://www.caswelleurope.co.uk/ for advise. Also, some places sell battery acid which should work - I think battery acid needs to be cut 50/50 with water to be the right strength for anodizing. for example...


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