Prepare the patio by cleaning it thoroughly. Use a mixture of soap and water with a scrub brush. You may need a wire brush to clean any bird excrement completely off the patio. Do not take short cuts. If the patio is not fully cleaned and cleared of debris, the moisture in the residues left behind will eventually cause the paint to crack and flake.
Fill any cracks or holes in the dried concrete with brick mortar or cement putty and allow them to dry before you continue. If you leave cracks or holes in the patio, eventually water will seep into them, freeze them during the winter and cause more cracking to occur.
Put the paint tray into a plastic bag and pour concrete sealant into the paint tray. The concrete sealer should have specific labeling as a moisture barrier. Roll the large roller brush into the tray, coating the brush with the sealant.
Start at the farthest corner away from the patio door and begin to coat the concrete evenly with sealant. Reapply sealant to the roller as often as necessary. Paint your way backward, toward the patio door to avoid painting yourself into a corner. Allow the sealant to dry.
Remove the plastic bag from the paint tray and apply a new plastic bag.
Examine the patio and sweep away or wash debris off the patio. If the patio is wet, you must let it dry completely before you begin to paint.
Pour the concrete paint into the tray.
Roll a new clean roller brush into the tray, coating the brush. Begin at the most-distant corner from the patio door and work your way back toward the patio door. Reapply paint to the brush as often as is necessary. Allow the paint to dry completely. The concrete patio is now painted.