Painting crown molding, ceiling medallions and ornamental plaster in an older home

To paint crown molding and ornamental plaster well, clean away dust and residue, check whether old layers are loose, repair cracks and caulk moving joints, prime bare or patched spots, and then apply several thin coats with a soft angled brush. Thin coats keep the detail sharp. One heavy coat fills it in and looks like icing.

Many older homes in Grosse Pointe and Metro Detroit have run-in-place plaster cornices, ceiling medallions and decorative ceilings and archways. They’re among the most beautiful parts of an older house, and among the easiest to ruin with careless paint. Here’s what to look for and what a careful job involves.

Why does old ornamental plaster look soft or clogged?

Because it’s been painted again and again. Each repaint adds a layer, and over decades the sharp edges of a cornice or medallion round off, the fine lines of leaves and beads fill in, and the shadows disappear. Eventually the plaster looks like it’s made of soft candle wax.

Look at the profile edges in raking light. A flashlight held flat against the ceiling shows soft spots, drips that dried in the grooves, and places where thick paint has cracked into a crazed pattern.

The answer isn’t always stripping. Removing every layer risks damaging the plaster itself, and it disturbs old paint that may contain lead in homes built before 1978. A careful painter works out which layers are loose and removes only those, then builds a sound surface on what’s left.

What should be checked before any paint goes on?

A short inspection prevents most surprises. Walk the room with a light and look for:

• Loose or drummy pieces. Tap gently. A hollow sound or movement means the ornament or the plaster behind it has let go.
• Cracks along the cornice. Hairline cracks are common; wide or sagging ones deserve a closer look.
• Stains. Water stains on the ceiling or cornice need their cause found, and the stain sealed, before paint.
• Peeling or flaking paint. It must be scraped back to a firm edge, which is where lead precautions matter.
• Dust, soot and residue. Cornices collect more of it than any other surface.

If something is loose, it isn’t a painting problem. Our guides to loose plaster repair and plaster ceiling repair explain how that works, and our wall and plaster repair page covers the service.

How do you deal with dust, wax and oil residue?

Cornices and medallions sit above radiators, near kitchens and over fireplaces, and they collect dust, smoke, grease and sometimes the residue of old cleaning products. Paint does not stick well to any of it.

A careful painter cleans from the top down: dry dusting first with a soft brush and a vacuum fitted with a brush attachment, then a gentle wipe with a cleaner suited to the surface, then a clean-water wipe. Plaster should never be soaked, so cleaning is done with lightly dampened cloths and kept brief. Any greasy or waxy area is cleaned again before priming.

Our guide to cleaning painted walls covers the general principles. Then comes the primer. Patched and bare plaster is porous, and it needs priming so the finish coats dry evenly instead of looking dull in patches.

Is there anything to be careful of before sanding or scraping?

Yes, two things. First, homes built before 1978 may contain lead-based paint. The EPA’s Renovation, Repair and Painting (RRP) rule requires certified firms and lead-safe work practices for paid work that disturbs painted surfaces in pre-1978 homes, more than 6 square feet per room inside. The EPA’s RRP program page has the details, and our guide to lead paint in older homes explains testing.

Second, some older plasters, joint compounds and textured ceiling finishes contained asbestos. If you plan to sand, cut or break any of it, have a sample tested first. Painting over sound plaster that you leave undisturbed is a very different thing from scraping it.

How are gaps and cracks along the molding handled?

Not all gaps are the same, and treating them the same is a common mistake.

• Where the molding meets the wall or ceiling. This joint moves slightly with the seasons. A flexible, paintable caulk, smoothed with a damp finger or tool, stays closed. Silicone isn’t paintable, so it’s the wrong choice.
• Joints between pieces of molding, such as inside corners, are caulked the same way and checked after the first coat.
• Cracks in the plaster ornament itself are repaired with patching compound, not caulk. Caulk stays rubbery and shows through as a line.
• Missing pieces of run plaster or ornament are a restoration question, not a painting one.

Caulk should be sparing. A thin bead into a true gap helps; a thick bead over a shadow line ruins the profile. And wait for it to skin over and cure before painting, following the label.

Which brushes and technique keep the detail sharp?

Ornamental work rewards a short list of tools. A good angled sash brush in the right size is the workhorse, with a smaller artist’s or detail brush for tight spots. For water-based paint, a quality synthetic brush holds its shape and releases paint evenly.

The technique matters as much as the tool:

1. Load lightly. Dip about a third of the bristles and tap off the excess, never wipe on the rim.
2. Work the detail first, pushing paint into the recesses, then lighten the stroke along the high points.
3. Watch the grooves. Check constantly for drips and pooling, and brush them out before the paint skins.
4. Cut in carefully. The line between ceiling, molding and wall should be crisp, and a sharp angled brush gives a better line than tape alone.
5. Keep a wet edge along long runs so lap marks don’t show.

Cutting in is where most of the visible quality lives. Our guide to painting ceilings and our guide to painting stair halls and high ceilings look at working on tall rooms.

How many coats, and what color and sheen suit the plaster?

Plan on at least two thin finish coats over primer, with the paint label’s recoat time between them. A thin coat lets the detail show through, and a second coat evens out the color. If a surface needs a third, it’s still thin.

For color, there are two classic approaches. A tone-on-tone treatment paints the molding the same color as the ceiling or walls in a different sheen, which makes the shadows do the work. A contrast treatment paints the molding white or a slightly different color from the ceiling, which defines the profile. Neither is wrong; the right choice depends on the room, the light and how much detail there is. Our guide to Sherwin-Williams whites compares the whites often used for trim, and our Color Studio helps with the palette.

Ceilings are usually flat, and cornices are often satin or eggshell, which catches a little light along the profile without highlighting flaws. Our paint sheen guide compares the choices. Test a sample before you commit; low light and sheen change how the color reads.

What does careful work on ornamental plaster look like?

Check it by the same raking light you started with:

• Detail reads clearly. Leaves, beads, egg-and-dart or fluting have visible edges and shadow.
• No drips or pooling sit in the recesses.
• Caulk lines are smooth and invisible once painted.
• The cut line against the wall and ceiling is straight, with no ragged edge.
• Color and sheen are consistent around the whole room.
• Nothing has been painted shut or filled in, including grilles and fixtures.

That’s the standard Guiffre’s Painting Co. works to on every project: floors and furniture protected, surfaces cleaned, loose paint scraped, holes and cracks filled, joints caulked, bare areas primed, and Sherwin-Williams paint in even coats. Our interior painting page explains what it covers, and our guide to painting plaster walls goes into the surfaces underneath.

Questions

Painting an older home in the Pointes?Plaster, original trim and old windows need a careful approach. Here’s ours.→