First of all you must carefully prepare the surfaces that you want painted. It should be clean and dry, without residues of the hydrophobic grease and other contamination. Additional training is not required unless you plan to paint polystyrene or ABS plastic water acrylic paints.
If you need to dye polypropylene or polyamide, the surface of the plastic must be pre-treated with adhesion promotor for polypropylene, which is applied by spraying or wiping. After that, the promoter must be allowed to dry for 1 minute.
Remember that the temperature of the dye, plastic and painting equipment must be the same. The ideal room temperature should be not less than 18 degrees Celsius at humidity of 80%.
As a rule, the painting is done in a single layer with a minimum thickness of 60 microns. If you make a film of lesser thickness, it may affect the adhesion of paint to the plastic. If you paint the surface of a thickness of > 120 microns, it will lead to a significant increase of the period of drying, which in turn may adversely affect the decorative effect of the coating.
Drying of polystyrene and ABS plastic, it is possible at a temperature of from 18 to 60 degrees Celsius. For example, when the wet film thickness of 80-120 microns and a temperature of 50 degrees Celsius (humidity about 65%) the drying time is 2-3 hours. If you dyed polypropylene and polyamide, at a temperature of about 100 degrees Celsius drying will occur in about 20 minutes.
It should be remembered that the cured paint coating on plastic is about 5-7 days. It is a big thick wet layer, low temperature drying and high humidity can increase this period several times.