[Zeke]

Spraying with back brushing is not only acceptable, it's preferred. The spray drives paint into the the small cracks and brushing works the paint into the surface. BTW, if preparation is perfect, spray will adhere chemically better and may not need brushing. Brushing ensures that paint is well worked into surfaces that may not be that well prepped. It also works paint behind things like the sand surface of stucco or the porous surface of masonry. A perfectly prepped smooth surface will take a good spray job nicely.