Only good thing with hammerite, is that it can be really thinned (something like 2 thinners to 1 paint) which will get it into crooks and crannies and still cover reasonably well, but without the hammered finish, (which is where the pinholes come along) though not a fan of it myself, having used it over the years and got poor results.Proper job.
1st if possible sand blast. If not sand down & remove all rust. Smooth bare metal with 1200 gauge wet & dry sandpaper. Primer then covers all with out small metal spikes with out compromising the coverage.
2nd. apply by hand brushing Red Oxide Metal primer. Been proved over many years in the building industry. Brushing is best as you get better & thicker coverage.
3d. Dulux undercoat & gloss (or similar) all handbrushed. Hand brushing will give a better thickness & coverage with little chance of pinholes.. Plus you only get the paint on the chair. Providing the preparation is good handbrushing will be smooth always be better in wearing qualities. That is unless you have professional cellulose facilities.
Regret but having once use Hammerite on metal on a boat found it is porous. Due to its nature very minute pin holes form & water gets through those pinholes.
May be ok over a primer. On the boat pin hole rust occured in a week & not just one pinhole. It is also very brittle.. Never used within the building industry..
Laurie
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