Previously Painted Surfaces
Before repainting a surface, you need to establish what kind of paint is on it. Remove a little of the old paint. If it is flexible with a plastic texture, it is likely latex; if it is brittle, then it is oil-based. Another way to tell is to apply heat to the surface. If it bubbles and melts, the paint is oil-based; if nothing happens then it is water-based. The general rule is that you cannot paint latex over oil because it won’t stick. However, there are now some latex asian paints that allow you to do just that.
Latex asian paints are now available for almost every application. Manufacturers are taking heed of the movement toward eco-friendly materials so that water-based asian paint, sealants and varnishes are as hard-wearing as their oil and solvent counterparts. But always check labels for suitability for purpose. There are still some instances, however, when oil-based paint is preferable. When creating a special finish, such as marbling, or where a very hard-wearing surface is required, oil-based paints are the best choice.
Latex asian paints are safer than oil-based, although basic precautions should always be taken when painting. Oil paint gives off fumes that can be dangerous, so ventilate the area when painting and while paint is drying. Oil-based paint also is flammable. Some old oil paint may contain lead, so take care when disposing of it. Contact your local waste management service for advice.