My grandfather was a painter and he always said not to paint water-based paint over oil-based paint! I know, but you can paint latex paint over oil-based paint if you take the right steps in the painting process. What are those steps? You can use a rag dipped in denatured alcohol to determine if the paint on your house or surface is water-based or oil-based. There are many good oil and acrylic primers on the market today — either primer will do a good job.
Solved! The Rules for Painting Over Oil-Based Paint
How to Apply Latex Paint Over Enamal Paint | Home Guides | SF Gate
It's possible to paint over oil-based wood stain with latex paint if the painter prepares the surface properly. Painters need to remove as much stain as possible by sanding or scraping. Then, they need to clean the surface thoroughly, apply a primer and use high-quality latex paint. Applying latex paint over an oil-based stain was once impossible. However, modern technology has allowed paint manufacturers to develop acrylic latex that adheres to virtually any surface, including plastic and oil-based finishes. However, it's best to sand the surface and use a primer to ensure optimal adhesion, especially if the surface is outdoors and exposed to the elements.
What would happen if you apply latex paint onto an oil-painted surface? Simply put, the paint will dry, but it might not stick very well. In some cases, you would be able to peel the paint right off. However, this does not mean that it is impossible to paint over an oil-painted surface with latex paint — all you need to do is take the proper steps to prepare the surface.