Plastic model paint comes in two families that behave completely differently. Acrylic model paint is water-based, dries fast, cleans up with water and dominates miniature painting. Model enamel paint is solvent-based, dries slowly to a harder and glossier film, and retains a following among scale modellers for reasons that are real rather than nostalgic.
What acrylic is good at
Acrylic model paints dry within minutes, which suits the layering that miniature painting depends on: you can put a second coat over the first almost immediately and build a highlight in a single sitting. They thin with water or their own medium, they clean out of a brush before they set, and they release no solvent fumes, which matters when the painting happens at a kitchen table. The trade is a softer film than enamel, which is why varnish matters more for acrylic-painted models that get handled.
What enamel is still better at
Model enamel paint dries slowly, and that is its advantage as well as its inconvenience: a slow-drying paint can be brushed out to a genuinely smooth, mark-free finish, which is why it persists on large flat surfaces like aircraft and vehicle panels where acrylic brush marks would show. The cured film is harder and more durable. The costs are real: solvent thinners, ventilation, long waits between coats, and brushes that need solvent to clean. For 28mm figures the balance falls clearly to acrylic; for a large-scale kit it is a genuine choice.
Priming, and why bare plastic is the problem
Neither family grips bare plastic well, which is the practical reason acrylic paint for plastic models is almost always applied over primer. Injection-moulded plastic is smooth and often carries a trace of mould release, and paint applied straight onto it will lift at every handled edge. Washing the sprue or the assembled model and then priming solves it. This is the same reason that a model painted well and never primed will look fine for a month and then start showing bare plastic on every raised surface.
Questions people ask about plastic model paint
Acrylic or enamel for plastic models?
Acrylic for miniatures: fast, water-cleanup, no fumes. Enamel still suits large flat surfaces where its slow drying brushes out to a smoother finish.
Does acrylic paint stick to plastic models?
Only reliably over primer. Bare injection-moulded plastic is smooth and often carries mould release, so paint lifts at handled edges.
Can I use acrylic over enamel?
Generally yes once the enamel is fully cured, though not the reverse, because enamel thinners attack acrylic. Test on a spare piece first.