Sulphuric Acid.

[Andrew TinsleyParticipant @andrewtinsley63637]

I am getting very low on sulphuric acid that I use in my anodising bath. Seems that it can no longer be sold due to idiot acid attacks. I know that brick cleaner is mainly sulphuric acid, but what else it contains is any ones guess. Does anyone know of a substitute for anodising use?

Andrew.

[Clive Brown 1Participant @clivebrown1]

I thought that brick cleaner was based on hydrochloric acid.

[Thor 🇳🇴Participant @thor]

Hi Andrew,

For anodising aluminium Oxalic acid has been used. You should be able to get the sulphuric acid used in lead acid batteries/car batteries, although it will not be concentrated. Doesn’t brick cleaner contain hydrochloric acid?

Thor

[Dave HalfordParticipant @davehalford22513]

I thought brick cleaner is normally hydrochloric acid

[Mark RandParticipant @markrand96270]

‘professional’ drain cleaner is concentrated sulfuric acid, but it has colourants and detergents added as well, So I don’t know (yet) if it’s any good for anodizing. Bloody EPP regulations are insane.  Yes you can get a license, but then you’re spending regular fees to keep it up to date.

[vintagengineerParticipant @vintagengineer]

One Shot drain cleaner is 99% sulphuric acid and is available from Amazon.

[FulmenParticipant @fulmen]

Some report good results with sodium bisulfate which is sold as pH- from pool suppliers. It’s basically partially neutralized sulfuric acid so it should be compatible with dyes. I know both oxalic and phosphoric acid can be used, but these are not well suited for dying.

[Fulmen]

On Fulmen Said:

Some report good results with sodium bisulfate which is sold as pH- from pool suppliers. It’s basically partially neutralized sulfuric acid so it should be compatible with dyes. I know both oxalic and phosphoric acid can be used, but these are not well suited for dying.

+1 for Fulmans comment. If you look at my youtube channel , you will see me using Sodium Bisulfate. It works great.

Steve.    https://www.youtube.com/playlist?list=PLqxEUtyoHqnL4tSBHvkdooxe4QDurp7up

[Robert Atkinson 2Participant @robertatkinson2]

EPP licencing applies to any form of sulphuric acid over 15% concentration. This is at the low to mid range for anodising aluminium so you could look for 10 – 14% acid but it will cost more. You might find a supplier who will make it up for you.

Sodium bisulfate is probably the best solution no pun intended.

The drain cleaners sold retail that used to be H2SO4 have been reformulated often to sodium hydroxide. For example “one-shot” is now a powder.

Robert.

[old martParticipant @oldmart]

Getting a licence to purchase sulphuric should be straightforward. I would not touch anything over 20%, having been in the plating industry. I was standing at a sink with a tap running when I spilled one drop of concentrated sulphuric on my wrist, and it was under the running water in less than a second. Too late, it burned through the skin and was painful, leaving a 5mm hole about 2mm deep.

[noel shelleyParticipant @noelshelley55608]

send me a PM I may be able to help. Where abouts are you. Noel.

[Alan CharlestonParticipant @alancharleston78882]

Hi,

I was interested in Old Mart’s story about getting burned with concentrated H2SO4. I’ve always taken concentrated to mean 98.5% which is what it comes out of an acid plant as. “Strong” acids are defined by the amounts of free hydrogen ions in the solutions. The virtual absence of water in “concentrated” H2SO4 means it is actually classed as a weak acid. Once it is diluted with water however, it becomes a very strong acid.

The main hazard with concentrated acid is the amount of heat generated when it is diluted. If 98.5% acid is diluted to about 76%, the resulting solution will boil at about 160 degrees C. I suspect that Old Mart’s hand was wet when the drop of concentrated acid hit it and that he suffered a thermal burn rather than an acid burn. This is why getting it in the eyes is so bad – the acid is diluted by the tears covering the eyeball and boils.

Regards,

Alan C.

[Robert Atkinson 2Participant @robertatkinson2]

Getting a EPP licence is straightforward. The problem is it costs money and time. Note that it is an offence to supply (including gifting) as well as own prohibited substances, including >15% H2SO4, not just purchase .
Note that the requirement for a licence does not apply to professional or business use but reporting does. I have direct knowledge that reporting of “suspicious” chemical purchases is a functioning process……

Robert.

[Neil WyattModerator @neilwyatt]

I have had great success anodising with sulphuric acid at a concentration comfortably below the 15% limit.

Virtually all the black and gold surfaces on this telescope.

Neil

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