Before you start painting, prepare your trim or crown molding surfaces. Prep work takes time and effort, but it makes painting easier. And the results are longer-lasting, so prepping is definitely worth it.
Paint doesn't adhere well to dirt, so clean surfaces well before you begin. Dust and vacuum all surfaces to be painted. For crown molding, tops of windows, or door casings, use a stepladder or small extension ladder to reach up there.
Give even brand new trim a good, once-over cleaning just to be sure that the piece you're painting is fully prepped and ready to go. The cleaner your surfaces, the better the finished job will be.
Use a sponge dipped in phosphate-free cleaner and warm water to clean all of the woodwork. Use a soft brush for crevices and, if necessary, an abrasive cleaning pad for tough stains. Rinse the surfaces well and dry thoroughly with an absorbent towel.
Use plastic or canvas drop cloths to protect your floors from any paint that might drip or splatter. If your room is carpeted, and you're painting base molding, mask its edges with blue painter's tape, placing it against the molding and using a putty knife to push it beneath the edge. Most molding has a gap under the lower edge to leave room for the carpet; if yours doesn't, push the tape down as far as you can between the carpet and the molding.
Painter's tape should also be used to protect the edges of walls and ceilings that are adjacent to the trim and molding. Last but not least, if any hardware is attached to the trim, remove what you can and tape up the rest.
To protect twice as much carpet, use a double strip of tape. Place the second line parallel to the first, effectively doubling its width.
To keep paint from bleeding under the tape onto neighboring walls and ceiling, press the edges of the tape down with a block of wood to seal them tightly.
It's inevitable that some trim will see daily wear and tear. Dents, nicks and scratches can be very noticeable and distract from a room's overall appearance, so it's important to repair any imperfections before you start painting. Sanding works well to remove shallow dents or scratches. For best results, use sandpaper on a rubber sanding block, or a sanding sponge if the surface is irregular. Start by sanding with 80-grit paper until the dent or scratch is smooth, then finish, sand and feather into the surrounding area with 120-grit paper. Wipe the area clean with a slightly damp rag to remove any dust and grit.
Wood filler should be used on areas with more severe damage. First, rough up the surface with coarse sandpaper to ensure a good bond. Then apply wood filler with a putty knife. When it's hard and dry, sand it level.
Shine a strong light at a low angle across the surface of the trim to pinpoint any paint drips, brush bristles, chipped paint, dents and scratches that need to be fixed.
Lead is toxic, and scraping, sanding or removing old paint may release lead dust into the air. Children and women who are pregnant should stay away from the work area during this process. When you're working with lead dust, wear a NIOSH-approved respirator and clean all debris carefully with a HEPA filter-outfitted vacuum and a wet mop. Before you start, learn the proper methods to protect yourself by contacting the National Lead Hotline at 1-800-424-LEAD or visiting www.epa.gov/lead.
If your woodwork has a glossy sheen, it's important to dull it so that the paint will adhere effectively. To remove the shine, lightly sand the area with 120-grit sandpaper or apply a brush-on deglosser, which is available for latex or oil-based paints. Remove the sanding dust with a vacuum when you're finished.
A thorough de-glossing is critical if your trim was previously painted with oil-based paint and you now want to switch to water-based; if you skip this step, your new paint will not adhere or wear well.
To find out if your trim was painted with latex or oil-based paint, rub the surface with a rag moistened with denatured alcohol. Oil-based paint will not be affected, but latex paint will soften and stain your rag.
When you sand indoors, keep the air clear by creating an easy exhaust system. Set a box fan in an open window to circulate air and direct airborne dust outdoors.
As a safety precaution, observe all label instructions and cautions for using electrical tools and deglossing agents.