Select paint appropriate for your outdoor project. You will need a paint that is resistant to moisture and sun exposure. Outdoor concrete paint is available acrylic paint harmful to children outdoor projects. However, an oil-based paint also may work for your needs.
Pick a paint for your indoor paint project. Basement concrete paint is available in many paint and home improvement stores, however you also can use an interior acrylic paint for the project. For exterior projects, use a power washer to rid the wall of all dirt and dust. If your project is indoors, scrub the wall with soapy water and a scrub brush instead of using a power washer. Repair any cracks or blemishes in your wall with concrete patch. Follow the directions to mix up the concrete patch mixture.
Fill holes and use a trowel to smooth the patch to match the surface of the wall. Paint applied to a wall that is not properly sealed will not adhere properly. Tape plastic sheeting to the wall. Attempt to get the sheeting as air-tight as possible. Check the plastic after 24 hours. If moisture appears within the plastic, you will need to seal the wall. If no moisture is present, the wall is already sealed.