What causes flaking and blistering of paint on exterior brick and masonry surfaces?

The most common causes are moisture beneath the paint film and paint applied over dirt, oil, grease or onto a poorly prepared, powdery surface. Water-based coatings may blister if applied over surfaces previously painted with solvent-based paints or primed with a solvent-based stabilising primer that isn't thinned prior to application. To remedy the problem, scrape back all poorly adhering coating to a firm edge and abrade shiny surfaces with abrasive paper. Repaint with Weathershield Primer and Weathershield Arcrylic Exterior Wall Finish.