Whether finished with paint or stain, trim must be properly prepared. This normally means setting nailheads below the surface of the wood, filling and sanding holes, cleaning, and repairing or replacing damaged wood. It can also require the removal of old paint or varnish to provide a fresh surface for the finish.
It's best to have all the preparation work completed on both the trim and the walls before finishing either surface.
Be sure to wear protective glasses when stripping, and a dust mask when sanding. Chemical strippers can contain toxic fumes, so ventilate the room adequately before applying the stripping solution. Rubber gloves are also a must to keep the chemicals from burning your hands.
Step 1: Test for Lead
Lead is a hazardous material used as an ingredient in paints before the late 1970s. In 1978, legislation banned its use, but your house could still contain lead paint. There are prescribed precautionary steps you should employ in the removal of lead paint, and in some cases you'll need to call a professional to stabilize or remove these materials.
The best ways to abate lead-paint hazards in your house include:
- Paint removal: Scrape paint from peeling walls and woodwork with a broad knife. Wear a respirator as you work. You can apply chemical paint strippers to soften the paint. If you dry-scrape the paint, mist the surface with a spray bottle to reduce hazardous dust. Clean dust and particles with a wet mop—vacuuming it spreads lead dust. Sanding, sandblasting, and similar methods aren't recommended because of the dust hazard.
- Encapsulation: Instead of removing the paint, isolate it or seal it off. Apply new drywall over an existing wall or float the wall with wallboard compound.
- Surface replacement: Remove and replace woodwork and moldings that have been painted with lead paint.
Step 2: Remove Gloss and Fill Nail Holes
Even the best new paints or clear finishes will not adhere well to gloss paints. So, prior to painting with your favorite BEHR or Glidden paint, scuff-sand all glossy surfaces with 150-grit sandpaper. Do this before trim is attached to wall.
For large or small flat surfaces, a palm sander or random orbit sander is a great time-saver when sanding walls or woodwork. You want to sand with the grain, changing the sandpaper sheet often as it wears down.
Contoured surfaces are difficult to sand with rectangular sanding blocks because they can gouge the wood. Use flexible sanding blocks or sanding sponges to smooth these curved surfaces. If trim was already treated with paint, sand until the surface is no longer shiny.
After scuff sanding, the surface will contain microscopic dust particles left in the grooves by the sandpaper. Pull these particles off the surface with a soft cloth dampened in mineral spirits or water. Don't use a tack cloth; it can leave a residue that will interfere with the paint bond.
Recess and Fill Nails
Use the right size nail set to push nailheads below the surface of the wood. Place the point of the nail set in the recess of the nail head and tap sharply with a hammer.
If you will ultimately paint the surface, use a putty knife to slightly overfill the nail holes with interior wood filler. Sand it smooth when dry. For clear finishes, buy different colors of putty and use the one that most closely matches the finished tone of the wood.
Step 3: Patch Trim for Painting
Wash the surface of the trim with a TSP solution or a low-phosphate household cleaner. Rinse thoroughly with a vinegar/water solution, and let the trim dry. Use a stiff putty knife to scrape loose paint to the bare wood.
Apply high-quality latex wood patch in nail holes, dents, and other damaged areas. Overfill the area slightly to accommodate its tendency to shrink. Let the filler dry.
Sand the repaired area smooth with 150-grit sandpaper. If the filler has shrunk below the surface of the wood, reapply another layer and sand it after it's dry.
Step 4: Paint Trim
Install Trim and Prep Area
Unlike other paint projects, you'll want to install the trim before you paint it. Safely secure it to the wall with your desired technique.
Lay down a drop cloth that sits right up against a the wall. This important step will save your floors or carpet from damage if any paint drips off the trim. Mask off the trim with painters tape.
Prime and Paint
Use a brush to prime and paint the trim. Be sure to wait the recommended time between each coat. Paint in long strokes that go with the length of the trim. Satin or semi-gloss is standard paint finish for trim due to its durability. Let dry completely before you move furniture back into the room.
Tip: Do you have color questions, or aren't quite sure what type of paint to use? Visit The Home Depot's paint desk for advice.
Walls or Trim: Which to Paint First
First, lay down a drop cloth to protect your floors from any drips or spills. If you are an amateur painter, paint trim first with a paintbrush, then the walls. This strategy will make it easier to sand, prepare, and paint all the details, edges, and planes of the trimwork.
After all the coats of paint on the trimwork are thoroughly dry, mask off the trimwork with painters tape and paint the wall with a roller. Because you have masked the trim, any splatters from the wall should land on the painters tape, which will be removed later. Most professional painters would paint the wall first, then skillfully do the trim.
Pick the Right Paint Finish
Choosing the right paint finish for your trim is just as important as properly preparing the wood trim surface. Opt for a satin paint; it will display a light luster with a soft texture. Satin is more durable than flat paints and can be used for trim that won't get much abuse, especially when you want to set the trim apart from a flat-painted wall.
Tips for Trim Paint
Once you've completed all your prep work, it's time to paint trim. Prime trim with a primer, then topcoat the trim using either oil or latex enamel as desired.
Doors, windows, and moldings typically take a higher sheen than walls because they get more physical contact and need a tougher surface. In addition, a glossy surface accentuates the woodwork and makes it stand out from the walls. That contrast between trim and walls adds interest to your design scheme. Choose trim paint that's at least one step glossier than the walls.