Wouldn't it be nice to finally paint that unsightly concrete wall in the basement? Or to paint that exterior wall or patio? The bad news is that Spackle won't stick directly to concrete. Concrete simply holds too much water to be reliably adhesive for Spackle. The good news? There are several Spackle substitutes on the market designed to solve this problem, and most hardware stores carry what you need. With a little guidance, you'll be enjoying that painted basement or beautiful patio in no time.
Buy concrete patch, a Spackle substitute designed specifically for concrete and the best product to solve your problem. It can also be used on its own to fill holes since most brands dry gray in color, blending fairly well with concrete. Most hardware stores carry multiple brands of the product, available in either interior, exterior or interior/exterior versions. Select a "ready-mixed" or "pre-mixed" formula, and figure out how much you require. Concrete patch is sold by the ounce, quart or gallon. How much you need will depend on how many cracks and imperfections you intend to fill.
Prepare your surface by getting rid of loose pieces: The preparation you do now could mean the difference between needing another repair next year or in 10 years. Take a look at the cracks, fissures and imperfections you intend to fill. Are there loose concrete pieces? If so, it's wise to use a chisel to get rid of all masonry that looks as if it could fall off the surface soon.
Clean and dry your surface. Use a wire brush to clean grit and dust from your concrete surface. Then use a towel to make sure the surface is swept of any final dust or moisture -- a step particularly important in damp basements and for surfaces that may have seen rain recently.
Apply the concrete patch. Once your surface is thoroughly cleaned and prepared, it's time to apply your Spackle substitute. Use a trowel to patch up the holes, cracks and imperfections on your concrete surface in the same way you would use Spackle to prepare drywall. Smooth out the concrete patch as carefully as possible in order to have an even, paint-ready surface. Once the cement patch dries -- the duration will vary depending on the brand -- you are ready to prime and paint.