Painting Contractors, Plaster Walls and Why Interior Paint Peels

An older Pasadena house holds two separate buildings as far as paint is concerned. The outside is wood and cement plaster taking full sun, and almost everything written about repainting these houses is about that half. The inside is a different material that fails in different ways, and a crew that is genuinely good on a bungalow exterior can still hand you a hallway that sheds its new paint in sheets inside a month. When that happens, the cause is almost never the paint that was just applied. It is something that was already on the wall.

Interior walls in a house built here before the war are not drywall. They are plaster, usually three coats of it, trowelled onto thin wood lath nailed across the studs. The first coat is pushed through the gaps between the laths so it squeezes out behind them and hardens into keys, and those keys are the only thing holding the wall up. Over that goes a brown coat for thickness, then a very thin and very hard finish coat of lime and gauging plaster. The result is dense, slightly wavy, far harder than any modern wallboard, and it fails in ways that have nothing in common with drywall.

None of that is visible with the furniture in. A homeowner who notices a strip of paint curling off a stair hall wall and types painting service near me into a phone is trying to buy a finish, and what the house actually needs first is a diagnosis: what the plaster is doing, and what is already layered on top of it. Those two questions decide the whole scope, and getting either one wrong is what produces a repaint that looks perfect at the walkthrough and embarrassing by spring.

Most of the painting contractors pasadena homeowners interview have spent more of their careers outside, because that is where the volume is. Interior work on a century old plaster house is a narrower skill, and the questions below separate the crews who have done it from the ones about to learn on your dining room.

Hairline cracks are cosmetic. A drummy wall is not.

Plaster cracks. A house that has stood through a hundred years of seasonal movement and a few earthquakes carries hairlines radiating from door and window corners, running along lath lines, and wandering across ceilings. Most of them are old, stable and cosmetic.

The thing to establish is whether the plaster is still attached. Press the flat of your hand against the wall and push gently, then tap across it with a knuckle. Sound plaster is immovable and rings hard. A field that flexes under hand pressure, or answers with a hollow drum note, has lost its keys: the plaster has separated from the lath and is held in place by nothing but its own stiffness and the paint. That is delamination, and filling the cracks on a wall in that condition is painting a problem shut.

The repair is not plastering. It is reattachment, done with plaster washers: thin perforated discs driven through the plaster into the lath with a screw so the field is pulled back tight. They are set in a grid across the loose area, countersunk, then skimmed over. A crew that has never done it tends to propose cutting the loose plaster out and patching with drywall, which works but leaves a thickness change and a different surface hardness that telegraphs through the finish forever.

Cracks that are not cosmetic look different. They run in a straight line for a long distance, they step so one side sits proud of the other, they widen along their length, or they reopen every season after being filled twice. Those describe movement rather than shrinkage, and they belong to a different trade.

Patching plaster is not patching drywall

Lightweight joint compound is made to sand easily and to sit on gypsum board. On hard plaster it shrinks, it is softer than what surrounds it, and in a deep hole it cracks. Real plaster repair uses a setting type compound or a patching plaster that cures by chemical reaction rather than by drying, built up in lifts, over a bonding agent, because a century old finish coat has almost no suction left to grip with.

The layer that makes new paint fall off

Here is the failure that catches everybody. A homeowner repaints a bedroom ceiling, and within weeks the new paint lifts in large sheets with a chalky tan powder on the back of it, bringing some of the original surface with it.

That is calcimine, also spelled kalsomine: whiting bound with glue, the standard decorative coating on plaster walls and especially plaster ceilings for the first half of the last century. It was cheap, breathable, and never meant to be permanent. It has almost no water resistance and very little cohesive strength, so anything film forming applied over it is bonded to a layer of water soluble dust. The new paint is strong, it shrinks as it cures, and it pulls the calcimine straight off the plaster.

Testing takes a minute. Wet a small area with warm water and leave it: calcimine softens, turns slimy, and comes away with a rag showing bare plaster underneath, where modern paint ignores the water entirely.

There are two honest answers and one popular wrong one. The durable answer is removal: wash the ceiling with warm water and a sponge until no residue comes off, which is slow, wet, miserable work that cannot be done with the room in use. The other is a dedicated calcimine recoater or a solvent based sealer made to penetrate and lock down a chalky distemper, over a surface scraped of anything loose. The wrong answer is a coat of ordinary primer, which adds one more strong film to the stack and accelerates the failure it was bought to prevent.

If a crew has never heard the word, that is the most useful thing you will learn during the estimate.

Old oil on the trim, and why new paint peels off in strips

The woodwork in these houses, baseboards, casings, picture rail and built in cabinetry, has usually carried oil or alkyd enamel for most of its life, and after decades of curing it is hard, slick and chemically inert. Water based paint rolled straight onto it has nothing to grab. It dries, it looks excellent, and then a fingernail or a vacuum cleaner takes it off in a flexible strip the length of the board.

The fix is mechanical and chemical together: clean it, because a century of hand oil and furniture polish sits on a baseboard, sand or chemically degloss it so there is tooth, then prime with a bonding primer made for slick surfaces. A modern waterborne enamel over that performs very well and will not yellow the way an oil enamel does in a room with little daylight.

Finding out which it is takes a cotton pad and denatured alcohol on an inconspicuous spot: latex softens and transfers colour, cured oil enamel does not. Test three or four surfaces, because a hundred years of occupants means the hallway and a back bedroom frequently do not match.

Primer by condition, not by habit

Interior primer is not one product and the decision is made surface by surface. Bare plaster exposed by repair needs a primer that seals suction. Water stains from an old roof or an upstairs bathroom need a stain blocking primer, and they need the leak found first, because a stain that is still wet comes back through anything. Slick trim needs a bonding primer.

Sheen, and the honesty of an imperfect wall

Sheen decides whether a century old wall looks beautiful or looks damaged, and it is routinely chosen for the wrong reason. Gloss reveals geometry. The more sheen a surface carries, the more it reflects light at a consistent angle, and anything that breaks that angle, a roll in the plaster, a floated patch, a filled crack, a lath line, becomes visible. On a genuinely flat wall, eggshell and satin look rich. On an undulating plaster wall lit by a window at one end of a room, satin maps every imperfection with complete accuracy.

A flat or matte finish scatters light instead, and the same wall reads as a soft even plane, which is why modern washable mattes made for high traffic interiors have become the sensible default in old houses. So the convention here is matte on walls, always flat on ceilings, where any sheen at all shows every lath line across a whole room, and satin or semi gloss on trim and doors, where the sheen is doing useful work: it marks the architecture, it takes handling, and those surfaces are small and were built straight.

Living in the house while it happens

Almost nobody moves out for interior painting, and staying is entirely possible, but only if the job is sequenced for it rather than run for the crew’s convenience. The fast way to paint a house interior is to empty every room into the middle, mask the whole floor plan and spray. Room by room with brush and roller costs more in labour and takes longer, and it leaves you somewhere to sleep every night.

The sequence that works is bedrooms first, one at a time, so there is always a finished room to sleep in and a next room to move the beds into. Ceilings before walls and walls before trim inside each room, because dust and spatter travel downward. Closets painted with the room they belong to rather than left for a separate visit. Hallways and the stair hall last, because they are the circulation route and painting them cuts the house in half.

Dry time is what people underestimate. A waterborne wall paint is dry to touch in an hour and is not cured for days, and it is the cured film that resists a chair back or a bedside table. Trim enamel is worse: a door painted and shut against its stop before the enamel has hardened sticks to the stop and tears when it is opened.

The real disruption is not paint, it is dust from sanding patches and deglossing trim, which crosses a whole house on air currents in minutes. Doorways to rooms not in use get sealed with plastic rather than closed, return air grilles get covered, the heating and air system goes off while anyone is sanding, and sanders run connected to a vacuum with a fine filter. Interior coatings in a house built before the late nineteen seventies may also contain lead, which is a regulated subject of its own and worth asking about directly.

What a good interior scope says

It names the condition of the plaster and how any loose field will be reattached. It says what the existing coatings were tested to be, by what method, and what happens if calcimine turns up on the ceilings. It states which surfaces get primer and why. It specifies sheen by surface and by room. And it describes the room sequence and the dust containment, because those are the parts you will live with. An estimator who answers all of that standing in your hallway has been inside houses like this before, and on a plaster house that experience is most of what you are buying.