These have been used before for rust treatment of tins, but I used them consecutively (12 hours for each), and I am very pleased with the results. It could be dangerous to mix them together, but they work great one after the other with a cold water wash in between.
@Twoberth That’s a fine result. I’ve used the Hammerite for that task but not phosphoric acid too. I’ve supposed that that’s what the Hammerite mostly consists of, though I’ve not checked the label.
Hi, I believe that the active ingredient of Hammerite gel is 10 -25% Citric Acid: https://www.hammerite.co.uk/files/2017/02/HM_GB_EN_RUST_REMOVER_GEL.pdf Best Regards, Kerophile.
Nice result.there @Twoberth. I have the Hammerite, but yet to actually find a phosphoric source. I think I looked a while ago but can't remember the link now. I've several waiting patiently for me to get my act together.
coke for phosphoric acid, the cheaper stuff is fine coke was used to clean out clutches in rally cars so it must be good for you...
Cheers @ally, I'm off to check the large stack of Diet Cokes we have. Thought it might be a little too agressive for just rust conversion purposes and I'm not sure if anyone has mixed wallpaper paste with it either.
Courtesy of my local Ye Olde Hydroponics Shoppe. 85% phosphoric, 250ml for £3, which should last a little while. @kerophile I'm aware the GSR was citric based, but is there a recommended dosing strength for phosphoric? Eg 1/4 pint of paste to table spoon of 85% acid. I appreciate the time factor for varying strengths, eg painting on undiluted may take 10 mins, but a 20 to 1 in paste could be left for say 12 hours as @Twoberth did.
@Simes I bought 5 litres of 85% phosphoric acid off t'internet for under £20 in 2017. I immerse stove tins in it in a large washing-up bowl. I diluted it only so that I could fully immerse Optimus 111 and Shinabro 340 size tins, so I probably made about 8 litres at about 50%. An overnight soak does the trick. I have used it on 25-30 tins by now, topping up as necessary. It is likely to be only 40% by now but it still works fine. Incidentally, I bought it from a company called 'solvent-shop' which is no longer trading (insolvent?!), but there are many other suppliers.
Ta @Twoberth, my concern was it being possibly being a little too aggresive. Having had a bad experience previously with tin cleaning, I'm now very cautious. Damage that can't be undone isn't a situation I want to find myself in again. i have one particular project in mind which you have now given me confidence in tackling. Actually come to think of it I have a good practice piece. The Packaway tin missing it's stove. Pics to follow.
Hi @Simes I have never used Phosphoric acid with cellulose wall-paper paste. I find the Phosphoric acid pretty “sticky” as is on flat surfaces. I am also unsure of the potential chemical reaction between cellulose and a strong acid! Best Regards, Kerophile Best
Thanks George @kerophile For some reason I'd thought the GSR was Phosphoric based. Obviously confused between threads long ago. I'll do a trial run on the sample piece and see what happens. I'll try to remember to take notes. If dunking in 85% doesn't strip everything as the stuff I used last time did then I feel a bit happier.
That tin is impressive! Stateside phosphoric acid is easy to find at home improvement stores as a concrete etcher / cleaner.
