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A short film sharing what I’ve learnt about low current density anodising of aluminium from my limited experience in the home workshop. This isn't meant to be the right way, or even a good way, it's just the way I do it. The technique provides a measure of improved durability / corrosion resistance to parts, as well as changing the aesthetic. Note: The chemical baths can be reused over and over, so no need to remix for every job. o0o0o 00:00 - Materials used in this film may now be hard to source in the UK 00:30 - The importance of surface finish of the part 01:34 - Beware hazardous chemicals 01:50 - Dilute your chemicals the safe way 02:53 - Calculating sodium hydroxide etch bath dilution by weight 04:30 - Calculating sulphuric acid anodise bath dilution by weight 07:28 - Discussing anodising dyes 08:57 - Powering the anodising circuit 09:25 - A simple magnetic stirrer 09:45 - Cathode material and layout 10:21 - Estimating the surface area 11:03 - Using the 720 rule to set time and current 11:15 - Connecting the part to the anodise circuit 11:55 - Cleanliness is next to godliness 12:47 - Pre-anodise etch 13:02 - Setting the power supply 13:13 - Completing the circuit 13:57 - Dying the part 14:27 - Hot water sealing 14:40 - The finished part *Useful links and further reading* Changes to the rules surrounding the supply and possession of sulphuric acid in the UK during 2018: https://www.gov.uk/government/publications/licensing-for-home-users-of-explosives-precursors/licensing-for-home-users-of-poisons-and-explosive-precursors and https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/694030/FAQs_general_public_v4_-_Mar_2018.pdf For those speculating about the reason for the withdrawal of concentrated sulphuric acid products from general sale in the UK, this article might give food for thought: https://www.bbc.co.uk/bbcthree/article/5d38c003-c54a-4513-a369-f9eae0d52f91 https://youtu.be/9pZIl2EwlvY o0o0o Using sodium bisulphate in place of sulphuric acid: http://www.observationsblog.com/sciencetechnologyexperiments/anodizing-and-dying-aluminum-without-battery-acid https://www.youtube.com/watch?v=7jFN3l_mrKk o0o0o A 15% acid solution seems to be what many people aim for. There’s pros and cons to higher and lower concentrations but they’re beyond the scope of my little setup. finish.com has a wealth of information: https://www.finishing.com/11/30.shtml o0o0o Some 720 rule calculators. The one featured is by ‘kreutz’, mainly as I can use metric sizes with it. 1 mil is an optimistic coating thickness for sulphuric anodising -thicker coatings require hard anodising which is beyond the scope of this film. https://chemeon.com/p/calculator/ https://www.hobby-machinist.com/threads/diy-anodizing-at-home-720-rule-calculator-for-low-current-anodizing-method.6775/ o0o0o POST UPLOAD UPDATE: Some overseas viewers seem annoyed that the UK government would take steps to try to ensure the safety of their citizens by making it more difficult to obtain something that (a small minority of) the general public has demonstrated they're too stupid to have free access to. I dare say the persistent shopper will still be able to obtain it, but I wanted viewers to be aware of which side of the law both buyer and seller will be on if the relevant paperwork is not available. I should probably have said “small quantities of clean lead sheet are surprisingly hard to get hold of”. I've since obtained some from a friendly roofer 😉 I’m not a chemist, but I believe having too little acid to mix to the original calculation left me with a solution of around 14.5%. Given my ball park approach, I didn’t think it was worth the re-calculation / re-weighing / re-filming for a such a small difference. With concentration, time, temperature, current density and material all playing a part (and being beyond the scope of my simple setup) I just wanted to get on with it. Note: You can’t just divide the weight of acid by the weight of water to get a percentage, it needs to be the weight of acid by the weight of solution (i.e. acid plus water). I've had a few messages about MEK. Whilst not to be taken lightly, some comments might be an over reaction: https://www.gov.uk/government/publications/methyl-ethyl-ketone-properties-and-incident-management/methyl-ethyl-ketone-general-information Both etching with sodium hydroxide and anodising liberate gas. In a well ventilated workshop for a short time I see no issues. If you're in a sealed room for a long time, it may be something to take into consideration. Here are a few other clips where I use the same setup, with pretty good results: https://youtu.be/lNznefS02lE?t=146 https://youtu.be/iIxKXUGVJEE?t=769 https://youtu.be/KiYS3VVILCo?t=914 o0o0o Manually subtitled for accuracy (click the CC box) Shot: DMC-TZ30 1280x720 50P AVCHD Edit: FCP7 ProRes 422 Mic: C01U