We have bought a new home and all the interior walls are painted in semi gloss paint. We were given some very good quality paint but it is in flat. What do I need to do to the walls before painting? We were told that we would need to sand all walls.
Thanks so much.
Sanding is necessary if the semi-gloss paint is oil based or if your new paint isn't high quality 100% acrylic. If using a good acrylic paint over latex/acrylic, you just need to clean the walls and paint as usual.
Good acrylic paints can be painted over each other no matter what the sheen is. Here is a simple test for finding out if the paint is oil based or acrylic/latex.
Use a clean rag and denatured alcohol. Apply the alcohol to the rag and gently rub a spot on the wall. If any paint is softened or removed then the finish is an acrylic or latex paint. If no color is on the rag and the finish is still unaffected then it is an oil base.
Use a white rag for checking dark colors and a dark rag for light colors. This will make it easier to see any loosened or removed paint. Denatured alcohol readily dissolves acrylic and latex paints but leaves oil base paints alone.
Acrylic house paints cannot be applied over oil base paint without being primed first.