Most paints dry darker once they’ve been applied. Having said that, many factors affect the finish of paint products, so the comprehensive answer requires a bit more precision.
The first consideration is what type of surface you’re working with. A wood craft project will likely display a darker shade of paint without needing a primer of any sort. However, ceramics may appear lighter than the intended shade. Even though we are discussing walls here, the same theory applies to wall types. You may be dealing with drywall, to which you will need a primer. Paneling may also affect the end result with a dark wood bringing out the darker tone in the paint and a light paneling lightening the shade of color. And, of course, any underlying color will affect the result of the new coat if you don't apply primer first.
Another huge contributing factor to the finished look of your project is the lighting in the space. Have you ever held a sample in the store thinking it’s perfect and then tack the same sample to a wall at home with widely varying results?
Lighting alone can seemingly change green to grey and blue to purple. Natural light brings out the most accurate shade of paint, all things being equal. So place your samples next to the windows and glass doors to predict the color results.
Light bulbs skew the shade, muting or turning up the volume on everything from tan to red. Incandescent, fluorescent, halogen, or LED bulbs will all offer differing results. Some will cast a yellow hue while others may appear bluish. For larger projects, get a sample can mixed and apply it to different areas of the wall before committing to a larger quantity of paint.
3. Type of Paint
Perhaps the biggest influence on paint shade is the type of paint you use. Flat paint has a dull finish. This allows it to cover inconsistencies in the wall behind it, but it will have an almost powdery finish that can make your color selection appear lighter.
Moving up to semi-gloss or gloss will reflect more light, rather than absorbing it, often resulting in paint drying to a darker-looking shade. Matte or eggshell finishes are often the most likely to present a true reflection of the color swatch you fell in love with. Since they don’t reflect or absorb light, all other things being equal, the paint should look very similar to the sample when dry.
4. Prep Work
How you prepare your surface has an enormous impact on the end appearance. If you are painting over a lighter color and didn't get complete coverage the lighter color will bleed through not showing the true color of the new paint. On the opposite side of the color spectrum, if you paint over a dark color with a lighter one, expect those dark tones to haunt your lighter shade.
To create the ideal surface for your color choice, talk with the paint professional at your paint center. Explain the existing wall color and surface finish. Ask about the right primer to transition from what you have to what you want. Most of the time, your primer will need to be tinted to facilitate that transition. For example, if you hope to achieve a red wall, you’ll likely first apply a pink primer. Even though some paints claim to be paint and primer in one, that helps the paint to adhere to surfaces that may otherwise need a primer, but does nothing to cover one color that is vastly different from the one you’re applying.
6. Number of Coats
Most paints, even many of those that claim they will cover in one coat, need more than one layer to truly bring out the correct color. If your color doesn’t look right after one coat, the tone isn’t likely to change with more paint, but the shade could. Apply a second coat and allow it to dry completely before making your assessment. You don’t have to apply it to the entire wall or room. Simply create a sample space and, if you like it, continue with the project. If you don’t like the results, it’s time to take the paint can back to the paint center and ask them to remix it with a darker or lighter finish.