We hired someone to spray paint metal stairs with Rust-Coat interior/exterior alkyd paint. He diluted it with Natura Safe solution, a water-based paint thinner for oil-based and urethane paints. It has been over 48 hrs, and the paint is still tacky. It was only one coat. Does anyone know the approximate drying time for this? Any input would be very appreciated.
Curing time for alkyd base paint can vary but I would recommend waiting at least 1 week. Temperature will also affect curing time. If you notice the coating hardening after a week then more time all you need for it to fully cure. If it's still tacky then you might want to research the thinning material a a bit more. Compatibility or mix ratios might be reasons the coating won't cure properly.
Also, be mindful of dust if you decide to blow air onto the stairs. Dust will stick to the coating and once it's on and sticks, it's on for good.
I painted a set of cabinets with Tremclad Rustoleum low VOC, and was surprised to see that even after 3 days they were still not dry. It took over a week. Apparently since they switched the formulation to low VOC some years ago this paint takes ages to dry.
Check the can for info on the dry and recoat times, it may not be unusual.