Paints can either be oil based or water based and cannot be combined because the results will be disastrous. Water based paints cannot stick to oil based products so it runs or peels, and oil based products cannot penetrate wood and can never set if there is water paint on top of the surface.
If you examine the surface of a building you will know if oil based products are used because they sink inside the wood, make the wood grain visible, change its color and enhances its looks. It is now more difficult to determine oil based products based on transparency because of the use of non-transparent stains which covers the wood surface and make it look like paint.
If you find it difficult to find out if the paint is oil based or water based since they often have the same characteristic, try the goof off test instead. Goof off can easily remove grease, markers, and latex or water based paints, so if you rub a rug with a bit of goof off and the paint starts coming off, the paint is water based. Your local hardware store usually sells goof off and you can simply buy it there. There are many goof off brands available and choose the one where it says that it removes latex paint. Choose a part of the wall that is quite hidden when you do your goof off test. When walls are peeling it will be hard to determine with goof off test although it is not impossible because you can still observe what happens when you put goof off and if it peels or seem to melt or if it bubbles then it is a clear indication of being water based.
Latex or water based paints might be ideal for your project because it is easier to use. In the past, oil based paints were primarily used for buildings and that is why you see many old buildings having oil based paints. Coating a solid oil based painted wall with a primer will make it possible to repaint it with latex or water based paint. This primer will bond with the wall and provide a surface for the latex paint to stick to. Paint distributors will know what type of primer to deliver with your latex paint by simply describing what you are doing for your building painting project.3 Businesses Tips from Someone With Experience