Types of Paint
Acrylic
Acrylic paints are the most common paint types used on model kits and dioramas. Acrylic paint is easy to handle as it is water-based, signifying it can be thinned with and cleaned up with water. However, the use of acrylic thinner or airbrush flow improver gives the best results. Acrylic paints are vulnerable to scratches or marks, so it is important to topcoat your model kits with a varnish to help protect them. Depending on the temperature, Acrylic paint dries in around 20 minutes and cures within 24 hours. For airbrushing, alcohol-based thinners dry faster than water.
Advantages
Water-based acrylics tend to dry quickly, have a negligible odour and can be easily blended with water or thinner. Water can also be used to clean brushes as well as removing a topcoat to create chipping effects. Because of the fast-drying time, this allows many more coats of paint can be applied during a modelling session, thereby increasing the building of more complex areas, such as cockpits and figures.
Many manufacturers now produce a wide variety of paint ranges of colours designed to replicate real-life paints used by many countries throughout history. This makes it easier to produce a range of models with accurate paint schemes and finishes.
Nowadays, many manufacturers produce acrylic paints that are suitable for airbrushes, such as, Vallejo Model Air, MIG AMMO and AK Interactive. Airbrushing acrylic paint appeals to many modellers as these paints are relatively safe to use indoors and have little odour.
Disclaimer: When airbrushing paint, it is highly advisable to use a spray booth and facemask/respirator to protect yourself from the generated spray cloud.
Disadvantages
With their faster drying times, acrylics need some extra care to avoid brush marks on the model. This can be accomplished by applying multiple thin coats or the use of levelling thinners, drying retarders or flow improvers that can also be used when airbrushing acrylics, acrylic paint is prone to dry out in the airbrush, its tip or in the air on its journey to the model. Ambient temperature can also affect drying aspects.
The final finish is called by many a top-coat or varnish. It will help protect the paintwork from damage, as some model kits are designed for tabletop wargaming that is subjected to copious amounts of handling and repeated use.
Some brands of acrylic paint can be alcohol-based which give a sweet odour. This can cause issues when brushing painting because second or third coats can interfere with the previous paint layers.
Lacquer
Lacquer paints are the least commonly used due to their difficulty and risk of use. Lacquer paints are the hardest of the three main types and dry the fastest. Once dry Lacquer paints are extremely hard to remove without damaging the plastic as well. Of the three they are also the most toxic, so users should be in a well-ventilated area, using an explosion-proof spray booth that has a special fan system and wear a respirator, eye protection and gloves. Lacquer paint requires a different type of paint thinner fittingly named lacquer thinner.
Examples of Lacquer paint are MrColor and MRP (MrPaint).
Enamel
Enamel paints usually dry to a hard, glossy finish, It can take around 2-3 hours to dry, but has a 24-48 hour curing time. Because of this, Enamel paint dries harder, therefore, it is more resistant to scratches. Enamel paints are more toxic than acrylic paints but are not as bad as lacquer paint. It is used for hand painting where the slower drying allows for additional time for the paint to self-level and conceal brush strokes. Enamel paints are also recommended for panel washes.
Examples of Enamel paints are Tamiya Enamel, AK Interactive, and MIG AMMO.