Paint Preparation for Interior

I don't believe anyone likes doing it, but the interior paint preparation step is the most important task with any painting endeavor. I'll be talking about preparing walls for painting including some of the common wall repairs that you may encounter.

The key to a good-looking and long-lasting paint job is some painstaking preparation. With the proper tools, the paint preparation work will go much smoother and more efficiently.

Remember though, Safety Comes First - especially the proper use of ladders.

Let's start off with a checklist or agenda for going through the paint preparation phase...

Agenda for Proper Paint Preparation

1. Check for big problems. A sagging ceiling, for example, may be evidence of a roof leak or a seeping radiator on the floor above. Track down the cause of wall or ceiling damage and clear that up before you refurbish the wallboard or plaster.
2. Clear the walls. Take down pictures and curtains to look for cracks, holes, and peeling paint on walls and ceiling. Check the woodwork for loose paint, nicks, popped nails, and separations at corners or at wall junctures. If there is wallpaper, you'll probably want to strip it, whether you are painting or repapering.
3. Assemble your materials. For masking you'll need plastic drop cloths, newspaper, masking tape, plastic bags; for access, ladders and boards for scaffolding. For repairs, have on hand spackling compound, wood filler, a heat gun or chemical paint remover, sander and sandpaper, tack cloth, vacuum cleaner, and a spray can of primer. For cleaning you'll want detergent, bleach, bucket, and sponge; for safety, goggles and respirators.
4. Remove furniture and rugs. The more space you have to work in, the easier patching and painting will be. What furniture stays should be clustered in the middle of the room and covered with drop cloths. A rope tied around the bottom of the pile will keep the cloths in place.
5. Dismantle hardware. Remove knobs, latches, and locks on doors and wood window frames. Take down curtain rods and brackets. Remove picture hooks. Turn off electricity to the room; then unscrew plates from electrical switches and outlets. If there is a ceiling lighting fixture, either disconnect it and take it down or loosen its plate and enclose it - plate and all - in a large plastic bag secured at the top with tape.
6. Finish masking. Wall sconces, standing radiators, and thermostats need to be protected. Cover the entire floor (or carpeting) with plastic drop cloths, but ring the outer edges of the room with several layers of newspaper taped below the baseboards. Make a path of newspapers from the door into the center of the room. Newspaper absorbs wet paint and allows it to dry; plastic doesn't. Paint on a plastic cloth stays wet, and if you step on it, you are likely to track it into other rooms.
7. Make repairs. Fix walls, ceilings, and woodwork with the techniques described here and in my Common Paint Problems section
8. The last step in preparing walls for painting is to wash down all surfaces to be painted. Use a heavy-duty detergent such as trisodium phosphate (TSP) or a nonphosphate equivalent, bought at a paint supply store. Even fingerprints can keep paint from bonding properly. Clean any damp or mildewed areas with a 1:3 household bleach and water solution. Rinse, and let the area dry completely before painting. Glossy surfaces may also need sanding or an application of commercial deglosser for new paint to adhere properly.

Prepping the Room

Let me emphasize first that good surface preparation is essential to every professional painting job. The most expensive paint, the best painting technique and the finest brush can't compensate for poor surface prep. Doing a good job of paint preparation actually saves painting time. Once you've learned good paint preparation procedures, painting is a much easier task.

Painting is essentially the same from one job to the next. A door is a door and a wall is a wall. What changes is the preparation required. Every door requires custom paint preparation - a heavier sandpaper, a special primer, a different patching material, etc.

Begin by making a quick survey of the work required, step back and look at each room you are planning to paint as if you were seeing it for the first time. You may notice flaws you have learned to overlook but now have a chance to remedy.

Use a broom and a spackle blade as you make this survey. While looking over the walls and ceiling, sweep the broom along the baseboards and above the door jambs and window casings. Then check for spider webs along the ceiling and in corners. Sweep them off. Use the spackle blade to probe peeling paint, deteriorated plaster, cracked wallboard and rotted trim.

Common Repairs

Patching Cracks in Wallboard and Plaster

1. Before you begin scraping and patching, cover the spot on the floor under the wall or ceiling where you're working. This makes it easier for clean-up later.
2. Using your spackle blade or a screwdriver, dig out each crack a fraction of an inch on all sides. Be sure to remove all loose material along the edges.
3. Next, run your spackle blade or sandpaper down the length of the crack. That should remove any protruding chips of old paint or plaster and dust out the crack with a dry brush.
4. Then wet the crack with a paint brush dipped in water. While the crack is still damp, apply spackle with your blade. Do this in one long stroke if possible. Two thin patch coats are always better than one thick one.
5. When the first coat has dried, apply a second coat. Again, don't try to make it perfectly smooth. But be sure you have the crack filled at least flush with the wall.
6. When the second coat has dried, sand with number 220 grade sandpaper. This will provide a nice, smooth finish.

Patching Holes in Wallboard

The most simplest of paint preparation on the walls, just fill the small holes with one to two applications of spackle, and sand smooth.

Holes up to two inches wide that go all the way through the wallboard need special attention. Here's the procedure:

1. Remove any loose material around the edge of the hole.
2. Stuff the hole with paper so there's something behind the hole to hold the fresh plaster.
3. Then apply a layer of fast-drying compound. It usually comes in powder form to be mixed with water.
4. Leave the fast-drying compound slightly recessed, not flush with the wall.
5. Next, apply a layer or two of spackle, which is much easier to sand.
6. Sand until the patch is flush with the wall and smooth.

For holes between two and six inches wide:

1. Remove any loose material around the edge of the hole.
2. Use a proper size "wall bandage" to cover the hole. These wall bandages are available at all common home improvement and painting stores. They have a thin metal sheathing that is surrounded by a self-adhesive fiberglass mesh.
3. Apply a coat of drywall compound to cover the mesh and approximately 1 ½ inches beyond the edges.
4. Once dry, apply a second coat that extends another 1 ½ inches past the first coat. Try to feather the edges smooth to the wall surface.
5. Sand the area smooth.

Patching Holes in Plaster

1. Dig out all the loose plaster from the edges of the hole. With your blade or a screwdriver, dig the edges of the hole back at a slant so the hole is slightly larger on the exterior surface than it is on the interior surface. This expands the contact area so the patching plaster bonds securely to the old plaster.
2. Then dust out the hole and wet it with water.
3. Apply a layer of patching plaster with a wide blade. The depth of the plaster shouldn't exceed 3/8". If the hole is deeper than this, make two applications.
4. While the plaster is still soft, etch a grid-work of lines over the entire surface with your blade.
5. When this has hardened, wet the plaster and add another layer of patching plaster if necessary. If not, apply a coat or two of spackle and then sand smooth when dry.
6. If the hole goes entirely through the wall and the lath has been knocked out, use the wall bandage technique described in the paint preparation above.

Texturing Patches

1. If the existing wall has something other than a smooth texture, your patch should match that texture as nearly as possible.
2. Create a stippled effect by dabbing the surface with a sponge or stiff bristle brush while the patching material is still tacky.
3. Create swirls with a spackle blade. Dip the blade in water so it floats easily on the surface. Move the flat edge of the blade across the surface with a circular motion, the same way the plasterer's trowel was moved to create a texture in the existing wall.
4. To match a rough-textured surface, mix sand in the final layer of patching material. It's possible to match nearly any surface. The only limit is your creativity.

Wood Trim

The wood trim (baseboards, window and door frames) are another area to look after for the interior painting preparation steps. If it is in good shape, it will need little more than scrubbing with a strong detergent like trisodium phosphate (T.S.P.) before you can repaint it. Very glossy paint also may need to be sanded or treated with a deglosser so that the new coat of paint will adhere.

However, once paint on wood begins to crack or peel badly, it's better to remove it than to try to repair large patches. Taking off old paint is a tedious and messy job, but it creates a clean base for a durable new coat.

You can remove old paint with a heat gun or a chemical stripper. Nontoxic strippers work slowly - they soften old paint in hours rather than minutes - but they save exposure to caustic substances and fumes.

Bare wood - even though it has been previously painted - needs to be sanded smooth, wiped free of dust with a commercial tack cloth (or a cotton rag soaked in paint thinner), and sealed with a primer before it is repainted.

Repairing an Area of Flaking Paint

1. Scrape off all the loose paint in the area with a blunt flexible scraper, being careful not to gouge the wall. What paint is left must stick tightly to the surface, or your repair will not last.
2. Apply spackling compound to the edges of the patch area with a putty knife or wall scraper. Your aim is to taper the compound to eliminate the difference in thickness between the paint layer and the wall and return the area to a smooth, unbroken surface.
3. Level the patch with a broad scraper or another tool large enough to give an overall flush finish that fills in the paint edges without making any ripples elsewhere. Let the compound dry thoroughly.
4. Use a sanding block, first with medium-grit sandpaper, then with a fine-grit sandpaper, to complete the smoothing process. Wear safety goggles and a sanding respirator or a mask for this job.

Caulking Cracks

For another good paint preparation practice, it's very important to go around the room and fill in any cracks with proper latex "painters" caulking. This isn't just a matter of aesthetics, of course. Sealing cracks cuts down on air infiltration and reduces heating and cooling costs.

Use a caulking gun to seal cracks around door jambs, window casings, baseboards, where walls meet, and where the ceiling meets a wall. Dig out the crack with your spackle blade or a screwdriver. When all loose material is removed, begin caulking.

Hold the caulking gun at an angle and slowly run a line of caulk the length of the crack. Then run your finger over the line of caulk to even it out. A very good friend of mine who worked in the windows and doors business told me a little secret to get a nice caulking line that I'll share with you now.

Get yourself a little cup of warm water and add a drop or two of household dish detergent. Once you apply the line of caulking to the crack, dip your finger in the warm soap solution and then run your finger along the caulk line. Wipe the excess caulk on a damp rag that you should keep with you. What a difference it makes!

Also, when caulking in the bathroom or kitchen where wall tiles are in place, it's a good idea to first run your finger one way along the caulking line, wipe the excess off, then immediately run your finger the other way. Why? This way, you will get a nice seal along the edges of the tiles. You may notice if you do it one way, that there are still gaps or areas that your finger ran over and missed.

Bottom line - make sure that there are no ridges on your caulking edges - everything must be smooth before you paint. Dried caulk doesn't sand smooth but rather it rolls it up like a ball of rubber.

Repairing Nicks and Dents in Wood

1. Scrape away loose paint around the damaged area with a putty knife or wall scraper. Be sure all the paint you leave adheres tightly, or it will flake later.
2. Fill in the hole with plastic wood filler or spackling compound; then level the patch with a wallboard taping knife, and leave it to dry thoroughly before you begin sanding it.
3. Sand the patch with fine (150-grit) paper until its surface is even and smooth. The repaired area is now ready for priming with a primer compatible with the final coat of paint.

Fixing Separated Joints

1. Joints in door frames or window frames can pull apart as the wood shrinks. Small separations aren't serious and can be camouflaged with spackling compound or wood filler.
2. First check for popped nails. Countersink them with a hammer and nail set then fill the holes.
3. To fill joint openings in a stepped or decorative frame, use a flexible putty knife to apply the compound. Shape the compound to match the patter of the molding. If the opening is deep, you may need to apply two layers of compound. Sand the dried patch carefully to conform to the shape of the molding.

Treating Knots

1. Wood knots can bleed through paint to stain the finish, or they may ooze resin that hardens into lumps under the paint.
2. Firstly, use a razor scraper to remove resin deposits.
3. Clean the area with paint thinner or minerals spirits.
4. Seal knots with shellac or a special primer designed for this purpose. There are shellac-based primers on the market as well.

Preparing Specific Surfaces

Glossy Surfaces
Glossy surfaces should be sanded, washed with a solution of T.S.P., or treated with liquid sandpaper. This provides a roughened surface or "tooth" for good adhesion.

Calcimine
If you have to cover a surface that's been painted with calcimine or a similar coating, start with a thorough washing. Adhesion to the calcimine isn't the problem. Paint will stick just fine on a calcimine surface. But applying paint over calcimine seems to release the calcimine from the surface it is on. That causes peeling.

Mildew
Mildew is a parasitic organism that's common in damp, poorly-ventilated areas that get little sunlight. It needs either high humidity or a damp surface to survive. But mildew can grow on many surfaces including wood, concrete, fabric, and some paints. If you notice a dirty, mottled discoloration on a wall or ceiling, it may be mildew. Recognize it by its blotchy, powdery appearance.

If you suspect mildew, examine the surface carefully. It may just be dirt rather than mildew. Dirt washes off easily. Mildew doesn't.

Any surface that has mildew must be completely sterilized before painting. Scrub the surface with a mixture of 2/3 cup T.S.P., 1/3 cup powdered detergent, and one quart of household bleach in a gallon of warm water. Caution: wear rubber gloves and goggles when using this solution.

Once you've removed the mildew, take steps to keep it from coming back. Add either a fungicide or mildewcide to the primer and paint you use when repainting the surface.

Covering Up for Painting

As part of the paint preparation, the furniture should be moved to the center of the room and covered with plastic or wax-coated paper drops. If you're painting the ceiling, cover the furniture and floor with a regular drop cloth laid on top of a plastic drop.

Spreading out newspaper is no good. Newspaper shifts around as you walk on it, leaving part of the floor or carpet exposed.

If you're painting walls only, use a 3'x12' drop cloth called a runner. These are ideal when painting walls. A runner won't shift around like newspapers would. It's inexpensive and will last for years.

Cover light fixtures and doorknobs with paper or plastic held in place with tape. Here's how to mask around a light fixture:

1. First, turn off the light and loosen the screws that hold the base to the wall or ceiling.
2. Pull the fixture away slightly. Don't twist the fixture at this point. Some old wiring may have deteriorated to the point where any movement can cause a short.
3. Run a strip of tape around the fixture where it joins the wall or ceiling.
4. Then cover the rest of the fixture, or remove the glass globe when you're painting in that vicinity.
5. Turn the power to the fixture off if you cover it. Covered fixtures can overheat and shatter.

Be sure to cover items like air conditioners and curtain rods before beginning. Assume that everything in the room that could be splattered with paint will get splattered. Generally it's easier to move everything removable and cover everything that isn't.

Primer Application

Many people underestimate the importance of the paint primers during the paint preparation stage. It isn't just a cheap first coat. The primer of undercoater is the foundation that supports the finish coat. The best primer available for the job is going to be the best choice in every case.

Priming is always needed after patching plaster or wallboard. Spot prime the repaired area with a primer-sealer. When spot priming, feather the edges of the primed area and overlap the old finish enough to protect the adjacent area. If most of a wall was repaired, cover the entire wall with primer-sealer after spot priming.

Check out my article on specific paint primers here.