Give the surface a decent scrub with a stiff bristle brush to remove any dust or dirt.
Treat any fungal growth with a fungicide and allow to dry.
Fill any cracks or holes, if needed.
Cut open any old felt blisters and apply a coat of Isoflex Liquid Rubber underneath and secure with felt tacks.
For best results, use on a fine, dry day with temperatures above 10C.
Give the tin a really good stir before and during use.
Use a brush for this job and apply one generous coat across the whole roof.
It's just one coat, but on more porous surfaces you may need to apply a second coat after 4 hours.
Clean all of your equipment and any spills with Isoflex Clean up Fluid