Paints with higher-gloss finishes such as satin are often more durable than matte paints but also look dated and show flaws easily.
However, the higher gloss that paint has, the more difficult it is to paint. Since eggshell is a lower gloss paint than satin, it can have trouble sticking to the surface.
You can paint eggshell over satin finish paint as long as you prepare the surface, which allows the more matte paint to stick correctly.
If the Satin Paint Is Fresh
If you change your mind about a paint finish halfway through the job, the good news is that you can paint over satin with eggshell immediately without needing to do any additional prep work. As long as the satin paint was applied less than a few weeks ago (and has completely dried since then), you can paint as if it was a blank wall.
Painting Over Old Satin Paint
If the satin paint is more than a few weeks old, you will need to prep the walls before painting with eggshell.
The first step in painting over satin is to wash the wall. You will achieve the best results when using trisodium phosphate, an alkaline cleaning solution. Trisodium phosphate also flattens glossy paint and takes off some of the shiny finish.
Once the wall dries, after about 48 hours, then you can apply your first coat of eggshell paint. Apply primer first if the satin paint is much darker than the eggshell.
Once your first coat of eggshell paint dries, scuff the walls with a sponge like Scotch Brite. This helps take out the glossiness that shines through from the satin and eliminate flaws. Finally, you can apply the second coat.
You can paint eggshell over satin as long as the satin paint is fresh, or you scuff the paint in between coats to cover up any glossiness that might shine through.