Concrete walls are a blank canvas. They often have a cold and industrial feel. If cold and industrial isn't the design style you are aiming for, remedy the problem by polishing the walls to a high shine. Once the walls are sanded and polished, you can coat them with a clear sealer, stain them or paint them to match your décor. Polishing concrete takes some muscle. If you are feeling strong, you can do this job yourself with the right tools and a lot of hard work.
Wash the walls with dishwashing soap and water. Remove the soap residue by rinsing the walls with a sponge and clean water. Allow the walls to dry overnight.
Attach a diamond sanding pad to a hand-held grinder. A diamond pad is the only type strong enough to cut through the upper layer of concrete.
Press the grinder to the wall and begin applying firm pressure. Move the grinder up and down and back and forth across the wall. After a few minutes the concrete will begin to have a slight luster. You'll want a high shine for clear sealant and stain. For paint, it's necessary to remove only a small part of the top layer of concrete. Continue sanding until you get the shine you want.
Wipe the walls with a damp towel to remove the sanding dust. The wall is prepped and ready for paint, stain or sealer.