Preparing Trim

This story shows how to prepare trim for painting.

Preparing Trim

Door and window trim, as well as baseboards, cornices, moldings, and chair rails, make a major design contribution to the style of a room. 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.

Whether you finish your trim before or after painting the walls, 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.

Removing gloss: Step 1

New paint or clear finish will not adhere well to gloss paints. Scuff-sand all glossy surfaces with 150-grit sandpaper. Use a sanding block or palm sander on flat surfaces or a contour sander on curved surfaces.

Removing gloss: Step 2

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.

Filling nail holes: Step 1

Use the right size nail set to push nailheads below the surface of the wood. Set the point of the nail set in the recess of the nail head and tap sharply with a hammer.

Filling nail holes: Step 2

If you will ultimately paint the surface, slightly overfill the nail holes with interior wood filler. Sand it smooth when dry.

Filling nail holes: Step 3

For clear finishes, buy different colors of putty and use the one that most closely matches the finished tone of the wood.

Patching trim for painting: Step 1

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.

Patching trim for painting: Step 2

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.

Patching trim for painting: Step 3

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.

Preparing stained and varnished trim: Step 1

Clean varnished surfaces with a soft cloth and odorless mineral spirits. Scuff-sand the entire surface with 150-grit sandpaper.

Preparing stained and varnished trim: Step 2

Apply stainable wood patch whose color matches the surface closely. Level the patch and sand it smooth when dry.

Preparing stained and varnished trim: Step 3

Restain the patched area to match the finished surface. Apply the finish coat.

Removing paint with chemical strippers: Step 1

Apply a thick coat of stripper to the surface with an old natural-bristle paintbrush (many strippers will melt nylon bristles). Brush in only one direction to avoid lifting the stripper off the surface. Let the stripper work for about 20 minutes, then remove it and the paint with a scraper.

Removing paint with chemical strippers: Step 2

Reapply stripper where paint is still adhered and repeat the process. Remove small flecks of paint with a coarse abrasive pad, cleaning it with water or mineral spirits, depending on the stripper you've used. Finally, clean the surface with a fine abrasive pad dipped in denatured alcohol.

Sanding flat surfaces

For large or small flat surfaces, a palm sander or random orbit sander is a great timesaver when sanding walls or woodwork.

Sanding contoured surfaces

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.

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