There's an online chemical supplier that sells phosophoric acid, 85% for £3/l, compared to £12/l for the stuff sold as rust remover (which is probably also much weaker). Any reason not to use the cheaper pharma grade generic acid? This is for submerging rusty parts.
And is it enough to rinse parts or do they need to be neutralised?
And is it enough to rinse parts or do they need to be neutralised?