Some colors take two coats. Some take four. The difference is not the quality of the paint, and it is not the painter.
It is how much pigment there is room for in the can.
Why deep colors hide badly
Paint is tinted by adding colorant to a base. The base already contains the paint's own solids — resin, extenders, and titanium dioxide, the white pigment that does nearly all of the hiding in ordinary paint.
To make a deep color, the manufacturer supplies a deep base or accent base that has had most or all of the titanium dioxide removed, to leave room for large volumes of colorant without the film becoming too thick.
So a deep red is a lot of transparent organic colorant and almost no opaque white. Held up to the light it is closer to a stain than to a paint, and it hides accordingly.
| Base | White pigment | Typical coats over white |
|---|---|---|
| White / pastel base | High | 2 |
| Medium / mid-tone base | Moderate | 2 |
| Deep base | Low | 3 |
| Accent / clear base | Near zero | 3–4 |
The colors that need it
Worst offenders, roughly in order:
- Bright reds and crimsons — the classic four-coat color
- Deep yellows and golds — organic yellow pigments are very transparent
- Bright oranges
- Saturated blues and teals
- Deep greens
Better behaved: near-blacks and charcoals, which use large amounts of black pigment and are quite opaque; and any deep color mixed from an iron-oxide family, which is inorganic and hides well.
What tinting the primer does
The primer is tinted with the same colorant formula, usually at 50% of the topcoat's load, giving a mid-tone gray or a muted version of the final color.
The topcoat then has to shift the surface from mid-tone to deep, rather than from white to deep. It reaches full color in two coats instead of four.
| Approach | Coats | Paint used, 420 ft² room |
|---|---|---|
| Deep red over white primer | 1 primer + 4 | 1 + 4.5 gal |
| Deep red over 50% tinted primer | 1 primer + 2 | 1 + 2.4 gal |
Two gallons of the most expensive paint in the store, saved — plus a day of labor.
Most stores tint primer at no charge. It is worth asking for by name, because it is very rarely offered.
Gray scale systems
Several manufacturers publish a numbered gray scale — commonly P1 through P6 — and specify which gray to prime with for each color. Where the system exists, use it rather than a generic 50% tint.
The pattern is counter-intuitive: bright, clean colors want a light gray; deep, muted colors want a dark gray. Priming a bright yellow with a dark gray dulls it, because the transparent yellow lets the gray show through.
Ask for the gray number when the color is chosen. It takes ten seconds at the counter.
Where else it helps
White or light over a dark wall. The reverse problem, and tinting does not solve it — what solves it is a genuinely opaque primer with high titanium dioxide loading. Covering a dark wall is a different problem with a different answer.
Exterior accent colors. Front doors, shutters, and trim in saturated colors have the same base chemistry, and the same fix. On a door, four coats of an accent-base paint is a full weekend.
Ceilings under a colored wall. Not tinting, but related: most ceiling paints go on tinted pink or blue and dry white, which solves the problem of not being able to see where you have already been.
What tinted primer does not fix
Poor substrate. Primer seals and it does not level. A wall with visible joints or patches still shows them, and under a deep color in any sheen above flat it shows them more, not less.
Sheen variation. A deep color in satin over an unevenly absorbent wall reflects unevenly. That is a porosity problem, and it is what an untinted primer coat is for in the first place.
A color that was wrong. Two coats of a deep color is committed. Sample pots and a large test patch, viewed at the time of day the room is actually used, cost $12 and save the whole job.
Buying
For a deep color: one gallon of tinted primer per 1.3–1.5 gallons of finish, and buy all the finish paint in one batch. Tinted deep colors vary noticeably between batches because there is so much colorant in them, and boxing the gallons together before starting removes the problem entirely.
The second coat will go further than the first, but on a deep color the saving is smaller than usual — the second coat is doing color work, not just film build.