outside canopy slate tiles paint

Apply zinzer to the tiles first to avoid any further damage zinzer will seal the tiles for years to come then apply the finishing coat

After sanding the slate tiles I would use rustolem misty grey paint

Don’t paint it, put the right colour tiles on , stick with this mantra, “ do it right , do it once”

Any kind of paint requires a sound surface in order to adhere properly and stay put. Loose and flaky paint as a substrate is obviously not ideal, so that will need to be scraped off first. You can use a combination of wire brush, wallpaper scraper and sander. You don't have to remove all the existing paint, just the stuff that is flaky and loose. You must then apply a primer. That's the really important bit. The primer acts as a kind of 'glue' if you like and the topcoat will adhere to it really well. Spend your money on a good quality oil based primer (soluble with white spirit), such as Sandtex 10 Year Primer Undercoat. https://www.sandtex.co.uk/products/sandtex-10-year-primer-undercoat-paint If you want a gloss or satin finish, you will have to use an exterior quality oil based paint. Sandtex 10 Yr gloss/satin finish for wood and metal will be absolutely fine on exterior tiles and is available in a range of colours, which can be mixed if necessary to provide your own 'custom colour'. https://www.sandtex.co.uk/products/sandtex-10-year-exterior-gloss-paint