Yes, cement asbestos siding can be painted. First, because of the nature of asbestos, we suggest not scrubbing or cleaning it, or asbestos fibers may be put into the environment. If the surface is at all chalky (a white dusty material tends to come off onto anything that rubs against it) or is at all porous, first apply an oil based primer or sealer recommended for exterior cement asbestos siding. After this has been done, apply a top of the line exterior 100% acrylic paint in a flat or satin finish. The primer or sealer and the finish coat can be applied in hot weather as long as it is not windy and don't apply either in direct sunlight.