The basic trade-off
Sherwin-Williams' gloss and sheen guide puts it in two lines: lower sheen hides wall imperfections better, and higher sheen is generally easier to clean. Sheen is measured by bouncing light off the paint at a 60 or 85 degree angle, on a scale from 0 (no gloss) to 100 (mirror-like). In that guide's chart, the company's semi-gloss products mostly measure about 30 to 45 units at 60 degrees, and its gloss products 65 or more.
The same guide lists the factors that should drive the choice: the type of room, what is being painted, lighting, window position, traffic and how much cleaning you expect. So before you pick, look at the wall with daylight and your usual lights on. A wall beside a window, with light raking across it, will show patches and bumps far more at semi-gloss than at satin.
Kitchens: put the shine where the splashes are
Satin is a good default for broad kitchen walls, and Sherwin-Williams' finish guide lists semi-gloss for kitchens when easy cleaning comes first. You don't have to pick one for the whole room. A painter can use semi-gloss on the backsplash wall or around the stove and satin elsewhere in the same color.
If your current flat paint has shiny wiped spots, that is burnishing from scrubbing. Repainting in the same flat sheen won't fix it. Some washable low-sheen lines are sold as resisting burnishing and staining; the guide names its own Emerald and Duration Home as exceptions to the usual rule that shinier cleans better. Ask for the product's cleaning instructions and how long to wait before washing.
Bathrooms: sheen won't fix a moisture problem
Satin or semi-gloss both suit bathroom walls. But the manufacturer's contractor FAQ says ordinary latex eggshell and semi-gloss work in a bathroom “as long as there is good ventilation.” On damp walls you can get brownish streaks (surfactant leaching) or peeling. If paint is already peeling off in sheets, fix that cause first.
EPA's mold guidance says to keep indoor humidity below 60%, ideally 30% to 50%, run the exhaust fan or open a window when showering, and not paint over wet or moldy walls. If the mirror stays fogged long after a shower, check whether the fan is actually clearing condensation before you repaint. Persistent wet spots call for a plumber or ventilation contractor, not a shinier paint.
Trim: semi-gloss, unless you want it to fade back
Semi-gloss is the usual trim choice because it is easy to clean and gives moldings a crisp edge. Satin makes woodwork stand out less. Gloss gives the strongest highlight, and Sherwin-Williams suggests gloss trim against low-lustre walls for depth, but it also shows every flaw. The higher the sheen, the smoother the surface has to be.
In a pre-1978 home, the prep is the real question
Smoothing old trim for a shinier finish usually means sanding or scraping existing paint. EPA's lead renovation page says about three-quarters of U.S. homes built before 1978 still contain some lead-based paint, and that sanding or scraping it can create dangerous lead dust. Anyone paid to disturb paint in a pre-1978 home must be an EPA lead-safe certified firm.
Before you choose gloss trim in an older Philadelphia, Bucks or Montgomery County house, read what to check before sanding or scraping paint in a pre-1978 home, and make sure the bid covers it. Our guide to what a painting quote should say about lead-safe work lists what to look for.
What to ask the painter
- Which exact product and sheen are you quoting for each surface, and is it rated for kitchen or bathroom use?
- What prep is included, and which flaws will still show at this sheen?
- Can I see a sample board or a painted section under my room's lighting first?
- If the house is pre-1978, is your firm EPA lead-safe certified, and how will you contain dust?