Clean the alder cabinets with trisodium phosphate cleanser and a rag.
Remove the cabinet hardware. Often, you only need a screwdriver to take off the hardware.
Sand the alder cabinets with 220-grit sandpaper if they have a glossy finish. Glossy wood varnish doesn't accept new paint easily, but sandpaper creates enough surface texture for paint application.
Apply painter's tape to any nearby wall or counter surfaces. The tape protects these items from accidental paint drips.
Prime the alder cabinets with stain-blocking primer. Use a brush for edges and a roller for larger portions of cabinetry. Even if your alder cabinets are unstained, a stain-blocking primer is essential for alder cabinets. As a cut wood, alder releases natural wood oils. Without special stain-blocking primer, these natural oils will seep through paint and cause discoloration. Let the primer dry for an entire day before proceeding.
Paint the cabinets with oil-based paint. Use a brush for edge work and rollers on main surfaces.
Apply a second coat after two hours if you notice any bare patches.
Reattach the cabinet hardware and remove the painter's tape after 24 hours.