The primer you use under semi gloss paint can either enhance or detract from the finished paintwork. Avoid using matte white primer under semi gloss paint.
1. Semi Gloss Paint Highlights Surface Flaws
The silken texture and reflectivity of semi gloss paint, especially if you are using an alkyd (oil-based) formula, magnifies every flaw on the wall surface. Matte white primers have a rougher texture after drying than oil-based primers, and this roughness will be visible under the semi gloss.
2. Lack of Coverage of Previous Color
Many primers can be too sheer with one coat to cover existing color effectively under semi gloss paint. You can paint on two coats of primer for a more opaque surface, which takes longer and may still result in surface roughness under the final coat of paint.
3. Lack of Adhesion
Matte white primer in a latex formula will not allow the semi gloss paint to adhere as strongly as an alkyd primer. The primer may remain tacky for months, preventing the semi gloss alkyd paint from forming its trademark smooth, hard surface finish. Similar formulas for paint and primer make for better bonding, to give you the subtle gleam you want on your walls.