Depends On Tio2
The hiding of a paint product (except for low-gloss/sheen products, e.g.flat, satin, etc.), is dependent on two things — the amount of titanium dioxide pigment in the product and the thickness at which the product is applied. The exception for low-gloss paints is because the filler pigments used can contribute to hiding when the paint dries.
Major Color Change
When a major change in color is going to take place, from dark to light, there is a misconception that the surface should be primed before the first coat of finish is applied. The fact is that white, white base, and even some medium-tint bases have better hiding than a primer.
How To Improve Hiding Of Deep Colors
To improve the hiding of clear-base deep colors, it is helpful if they go over a tinted primer, or in the case of latex products on drywall, use the finish coat as a primer. When tinting a primer, it is advised not to exceed 4 oz. per gallon of tinting color. Latex eggshell or latex semigloss make an ideal primer for alkyd eggshell or alkyd semigloss on drywall. You can match the color exactly and reduce the number of coats required to get complete hiding.