Acrylic paint is a type of paint that uses a traditional pigment, but combines it with a polymer solution that bonds to the pigment and carries it to the surface. Acrylics typically use a water-based solution to dilute the paint, but can also use petroleum bases. Either way, acrylics are popular for a wide variety of surfaces, favoured for their bright colours and their waterproofing abilities.
Lacquering Over Acrylic Paint
Lacquers use a strong solvent to cover and protect wood. Typically, lacquers dry very fast and you will usually need to spray them on or paint them very quickly. Lacquer should always be mixed with lacquer thinner, typically in a 50/50 solution, before you apply it. Lacquers are very corrosive to other paint substances. The combination of the solvent and the thinner will almost always lift other types of paint, including acrylics.
Generally, there are many types of acrylic paints and many different types of lacquers, but you should not lacquer over acrylic paint or any other type of paint. The older the paint layer is, the more damage the lacquer will do, and the less effective it will be at finishing the wood. It will probably not make a large different whether or not the acrylic paint is water based or petroleum based.
If you do want to lacquer a section of wood painted in acrylic paint, you will need to first sand away the paint and reveal the wood layer beneath. New wood is best, but if you decide to sand the wood, make sure it is smooth, clean and dry before you begin. You can lacquer over surfaces that have been previously lacquered without sanding, if you choose.
When you lacquer, make sure to do it in a well-ventilated area, preferably with moving air. Gloves and a mask are also good ideas, because the fumes from lacquer are toxic, and the liquid is not safe to expose to bare skin. Try not to lacquer over the same area twice in one coat, and wait for coats to completely dry before adding any more.