I get the brush on stuff usually, i tried a can of the same stuff in aerosol form but it didnt seem to go as far, the tinned stuff goes on really nicely on rough metal, i like the finish, reminds me of the old red oxide when it actually worked!
Heres the rust treatment paint
https://www.buzzweld.co.uk/rust-encapsulator.html
and the gloss black is https://www.buzzweld.co.uk/classic-chassis-black-gloss-oem-mid-gloss-sheen-series.html
Neither are the cheapest products out there but they definitely are made to work! I've been following the guy who runs the company for a while on social media and he really seems to care about his products, loads of testing and new versions coming out.