According to DIY Network, sponge painting laminate countertops to look like marble offers an affordable alternative to replacing them. Using this approach, you stretch several more years from the average laminate.
Start with a clean surface
Use a mixture of warm water and vinegar to clean any dirt or smudges from the countertop. Provide ventilation and wipe the surfaces using denatured alcohol. Avoid touching the countertop after this wipe down. Remove any caulk around seams or sinks. Repair any large cracks or chips using epoxy putty. Tape anything that is not to be painted, taking time to ensure good adhesion so paint does not seep underneath the tape.
Degloss the countertop
Use 100-grit sandpaper to cut through the glossy surface and ensure good adhesion of the base coat. Use a tack rag to remove any sanding residue. Use a flashlight to ensure no dust remains.
Begin with a quality oil-based primer. Once it is applied, let it dry for 4 hours. Apply different shades of paint. First, apply a base coat of the darkest color, completely covering all surfaces. Apply a slightly lighter color with a sponge while the base coat is slightly damp. Use the same technique for the lightest color.
Protect the new finish
Apply a minimum of two polyurethane topcoats using a dense foam roller after the paint is dry.