Can you paint over acrylic?
Also question is, can you paint on acrylic?
Primer is usually a good idea (especially important for spraying metal), however in the case of clear plastic, acrylic, or glass, if you can complete the task in a single coat it is better. So choose a high performing acrylic enamel spray paint, or simply look for a paint designed to bond with plastic.
Also question is, can you paint over dried acrylic?
With acrylics, you can add wet paint over dry paint, or you can add wet paint onto wet paint. Most acrylic artists seem to work in this manner - allowing each layer to dry before adding another layer. Since acrylics dry quickly, this is a pretty straightforward process.
Alternatively, you can simply use acrylic paint. If the sealant is newly added it must be completely set dry before you can paint over it and as well as this, you must make sure that the sealant you purchase is actually paintable. Many old sealants are not and that takes extra preparation.