Chalking: Excessive and heavy powdering. Paints chalk naturally somewhat over long exposure to sun and weather.
Chalking probable causes: Usually due to natural weathering. Paints using excessive clay in place of titanium dioxide. Interior paints being used for exterior surfaces. Over thinning or spreading too thinly. Wrong product selection.
Chalking solutions: Remove all of the chalk dust with a stiff bristle brush (wire on masonry) and rinse thoroughly with a garden hose with high water pressure. For best and quickest results, use a power washer. If some chalk residue still remains, a chalk binder coat is required.
Primers & exterior finishes: A penetrating primer is essential to seal off any remaining chalk. Select a top quality exterior paint in the color and sheen of your choice.