To paint over oil-based paint with latex paint, first test for lead. Then clean and prep the surfaces to be painted. To prepare the surface to take the latex paint, use an acrylic-based bonding primer to seal the prepped areas. Once the primer has cured, apply the latex paint.
Using latex paint to cover oil-based paint requires several steps to insure that the latex paint won’t chip and peal. First, clean the surfaces to be painted with soap and water or vinegar and water. Make sure the area is completely dry before beginning work.
Next, test the old paint for lead, especially in homes painted before 1970. If the old paint contains lead, use masks and shop vacs to capture dust while sanding or use a deglosser to prepare the surface for primer and paint. If sanding, use a hard grit sandpaper followed by a softer one to give the surface teeth for the new paint to cling to. Be sure to vacuum up all dust and grit before opening the paint can. If using a deglosser, wipe off all the residue.
Paint with primer and let the finish cure according to directions. Then paint with latex-based paint. It may take as long as a day for the surface to cure and harden.