Bilt Hamber Hydrate 80 Rust Killer - 5 Litres

I've used on a classic car. Prepared metal by either mechanical methods (wire wheel, poly disc, scraping) or on smaller parts (e.g. bolts) the Humber Bilt Deox rust remover. Paint brushed two layers at 20 minutes apart. Surface stabilises into hard black blue layer. Then applied Red Oxide paint (Hammerite), then two costs of Jenolite Directorust. Time will tell how long lasts.I have given four stars and will update depending on longer term performance.I'm also going to experiment with different paints e.g. Zynga to see if can be applied too.Only downside so far is container difficult to open as Hydrate 80 can dry and seal the screw top lid. Bit annoying. Have used about 2.5l on car so far, with the chassis left.Whilst fairly costly, it's important to only do once. Hydrate 80 seems to be one of the better Bilt Humber products (they have a wide range of products, difficult to get all right), and is widely respected by professionals.As I want to use in engine bay, I asked Bilt Hamber for maximum constant temperature: it's 80C. I think most rust convertors are the same.