I just bought 5 litres of sulphuric acid from Gateros for anodising (which I haven't done yet). It will be less concentrated than battery acid for sure. I used to store my sulphuric acid at full 97% concentration and dilute it as needed until the law changed.

I use the water distilled from my garage dehumidifier for making up my electroplating baths with no ill effect.

Edited By Graham Stoppani on 21/05/2021 05:14:58

Yes dehumidifier water will be same as distilled but as Andy G says can be dirty.

Tony

Be-friend to your window washing people, or bribe them with tea, the ones that use long poles and lances with a pumped supply of water in the hosing.

They use demineralised water by the gallon so that the windows dry without leaving streaks. We have been using ours as a supply for years

Brian

I buy Demin' water from my local truck parts supplier in 25ltr containers for about £12 a go. We use it in the iron & for window washing.

regards

Sulphuric at just under the legal strength limit for unlicenced home use is fine.

I've used deionised water from a motor factors, available in 5L containers, got excellent results.

My tip is use professional dyes.

Neil

There's more purpose to the Acid than making the water conduct! Anodising grows a layer of oxide, and, if the layer is to be colour stained, it needs to be microscopically porous. A porous layer is created by anodising with an acid that partially dissolves the Aluminium Oxide as it forms, giving the layer a spongy structure to take the dye. Also, the acid should dissolve Aluminium Oxide but not the metal.

Not all acids dissolve Aluminium Oxide and others are too aggressive. 10% Sulphuric Acid is suitable and cheap, but my book says Phosphoric Acid and Oxalic Acid (Rhubarb!) also work.

May be worth trying alternatives like Citric Acid or Vinegar, but my guess is they either remove the sponge entirely, or leave it too thin to take a dye. Sponge size is also affected by the amount of current flowing and by the particular Alloy used. I suspect this is why results vary between excellent and abject failure! Using iffy materials and equipment at home it may be necessary to experiment.

Acid isn't used at all when a hard protective oxide layer is wanted; Ammonium Tartrate solution makes a thick solid layer that can't be dyed a pretty colour. No sponge!

Dave