Satin paint has a slight gloss and dries to a smooth velvety finish. The slight sheen adds warmth and dimension to a room without being garishly shiny. Semigloss has more sheen and is slicker and smoother to the touch. It reflects more light than satin paint. As a result, rooms painted with semigloss often seem brighter than those painted with the same shade of satin paint.
Satin is appropriate for walls that do not get a lot of wear. It is perfect for rooms that will not be subject to much wear and tear or water, dirt and grease. The slight sheen and wide color range make it an excellent choice for living rooms and dining rooms.
Semigloss is appropriate for areas that are frequently cleaned, such as children's rooms, or that can be damp, such as kitchens and bathrooms. It resists grease and dirt very well because the finish is not very permeable and it has a smoother, slicker surface. There are few places for dirt and grime to get trapped within the surface of the paint.
The more reflective a paint, the more likely it is to highlight small imperfections in the surface being painted. Satin finish paint does not show brush strokes as easily as glossier finishes. As a result, amateur painters find it easier to handle. Semigloss paint has a higher sheen and shows brush marks more easily. The painter must prepare the surface to be painted with care to remove any visible imperfections. Otherwise, these imperfections will stand out, highlighted by the paint's sheen.
On average, satin paint is cheaper than semigloss paint of the same product line but not by a large margin. Cost becomes more important in terms of the quality of the paint rather than the sheen. The higher the quality of the paint, the more expensive it is. The best policy would be to choose the highest quality paint product line you can afford and then choose between the satin and semigloss finishes depending on your needs.