Clean walls hold paint
Ask ten painters why a new coat failed early and most will point to the surface underneath it, not the can. Paint sticks to what it touches. If what it touches is a film of mildew, a layer of chalk or a smear of grime, the new coat is only as strong as that layer. In Baton Rouge, as anywhere, the first working day of a good paint job usually involves water, a cleaner and a lot of waiting.
The station figures
NOAA's engineering weather data for Baton Rouge/Ryan Field counts about 2,213 hours a year with the wet-bulb temperature above 73°F and about 3,994 hours above 67°F. Those are hours when the air is warm and holds plenty of moisture. Mildew is a mold that grows on damp, shaded surfaces and feeds on dirt and on some paint ingredients, which is why painters treat it as a surface to remove rather than a stain to cover. The figures are the station's own, set down as NOAA publishes them in the card below.
Telling mildew from dirt
A simple test helps you know what you're dealing with before anyone quotes:
- dab a dark spot with a cotton swab dipped in diluted household bleach;
- if it lightens within a minute or two, it's very likely mildew;
- if it stays dark, it's probably dirt, soot or a stain that needs a different cleaner or a stain-blocking primer.
Mildew left under new paint tends to grow back through it. Ask the painter how they'll kill it, how they'll rinse the cleaner off, and how long they'll let the wall dry before priming.
Chalk, the white powder on your palm
Rub your hand across old siding or trim. If it comes away coated in fine powder, the old paint is chalking: its resin has broken down in sunlight and left pigment on the surface. New paint over heavy chalk can peel in sheets. The fix is washing, sometimes scrubbing, and often a primer made to bond to chalky surfaces. A bid that skips this step on a chalky wall is a cheaper bid for a reason.
Washing without harm
High-pressure washing is fast, but on old wood it can raise the grain and drive water behind siding and around window frames. Many painters prefer low pressure with a cleaner and a soft brush. Questions worth asking:
1. What pressure and what cleaner will you use? 2. How will you keep water out of windows, vents and outlets? 3. How long will the house dry before you scrape or prime?
Older paint and the federal rule
If your home was built before 1978, the paint on it may contain lead, and scraping, sanding or hard washing can turn it into dust. EPA's Renovation, Repair and Painting Rule covers paid work that disturbs paint in homes, childcare facilities and preschools built before 1978: the firm needs RRP certification, sole proprietorships included, and the workers need training in lead-safe work practices. You can ask the painter whether the firm holds RRP certification and how they'll contain dust and debris. The EPA card carries the rule's exact words.
Louisiana's statute, briefly
The Louisiana card is there for reference. Its subject is R.S. 37:2150.1, which uses a $7,500 project value to mark home improvement contracting on an existing residence, along with the board's $50,000 point for its residential license. We print it as the legislature and the board word it and read nothing more into it.
How to compare Baton Rouge bids
Line up the proposals and check that each one spells out:
- the cleaning method, cleaner and drying time;
- how mildew and chalk will be handled;
- scraping and sanding, and how dust from older paint will be contained;
- primer: where, and which kind;
- finish coats: product, sheen and how many.
Our guide to drywall repair and surface preparation covers the interior side of the same idea, and the exterior painting page covers the rest of the outside job.