that's a phosphoric acid product meant to convert rust into iron oxide, if you scrape off a bit of the black it produces you'll likely find more rust. Scrub off the treatment w/water & a scotchbrite pad then sand down the metal w/80 grit & prep with an epoxy, skip the etch primer altogether if that what you had in mind. Oh yeah, throw away the K & H stuff & dont look back.

thanks mate you have saved me alot of messing around and fining out in a year that the rust converter dont work after i have painted it lol thanks for help:)

did u get a qoute from cameron at imperial blasting that is where i had my coupe blasted and and some claear coat sealer that you work over the top of it after scotchbriting it and it wasnt that expensive the cost outweighs labour and time spent doing by hand. are you painting it yourself?like edp said go with an epoxy etch none of that 1k crap honestly cant go past ppg dp40 or debeer washprimer as they both use catalyt and acids to etch int steel

na woodvile sandblasting i think they were called