yes, you can. It would be best if you have the painting stretched on a canvas. Otherwise the weight of the oil will cause the surface to buckle. Also, if it was my work I would want to put either a layer of clear gesso or spray Crystal Clear over the watercolor before using the oil paints. This will allow you to use solvents without disturbing the watercolor.
No, it will fall off like from a rainshield.
You can but it wont last, you will have a bigger peeling mess.
Water based paint such as latex and acrylic do not adhere well to oil paint. In order to paint over oil paint you must sand the surface and prime it with a good quality oil or alcohol based primer and then top coat with a water based paint. Oil based paints will adhere well to water based paints sp it is unnecessary to prime before top coating, unless you have had to do any repairs to the surface.
You can always paint latex ( water based )over an oil based paint as the latex just dries on the surface. However don't paint an oil based over a latex paint. Oil based paints need to absorb into the wood or other surfaces or it will just dry and flake off. For more information on the differences and when or not to use a latex or oil paint please see the following article. . http://www.ehow.com/how_4713170_between-latex-oil-base-paint.html
Water and oil do not mix. You will need an excellent quality primer specifically designed for this purpose. Answer: A good rule of thumb is never say no to a primer, but once the latex paint has dried, all the water is evaporated out of it. As long as the surface is clean, you can go over latex paint with oil without using a primer. If you do want to use a primer, use an oil based primer prior to topcoat.
You can use either a water or oil-based paint over a latex primer.
can i use water base paint over oil base paint
Yes, you can paint oil paint over sound water based paint easily, just be sure to degloss and clean the surface prior to painting.
No, you can't .
Yes. Clean and degloss the oil based paint, apply an oil based primer, then apply the water based paint.
Yes. Clean and degloss the oil based paint, apply an oil based primer, then apply the water based paint.
Yes, you can
You can but it wont last, you will have a bigger peeling mess.
Yes, if the original is in good shape, not flaky.
yes
That is not generally recommended.
Water based paint such as latex and acrylic do not adhere well to oil paint. In order to paint over oil paint you must sand the surface and prime it with a good quality oil or alcohol based primer and then top coat with a water based paint. Oil based paints will adhere well to water based paints sp it is unnecessary to prime before top coating, unless you have had to do any repairs to the surface.
That usually works quite well.