What are the different types of Auto Paint?

Automotive paint has changed dramatically since the late 1800’s.  We paint our cars, motorhomes, and motorbikes to protect the material that it is made from.

Rain and chemicals in the atmosphere can cause materials such as steel, and aluminium to corrode (rust), in order to slow this process down we give the product a coat of paint.

The four basic types of paint available today are acrylic lacquer, acrylic enamel, acrylic urethane, and water based.  We will drop the word acrylic, and just refer to them as lacquers, enamels, urethanes and water based.

Lacquer based automotive paint was popular between the mid 1920’s and 1960’s and is still available today, although it has become illegal in certain areas because of the amount of thinning agent required that may cause harm to the environment.  This type of paint was commonly referred to as cellulose paint.  It was used as it gave a high gloss shine straight from the spray gun, was easy to apply by inexperienced painters, and was available in aerosol spray cans.  The downfall was it was a soft paint which easily chipped, and wasn’t very resilient to chemicals and UV light (the sun).  It also soon became of a dull appearance, making it a short lived paint job.

Enamel paints dry to a hard shell, making them tougher than lacquer paints.  These are often baked on or in an oven to speed up the drying time; they are a lot harder to paint with, therefore requiring a greater skill level.  Once again, some enamel paints are available in aerosol cans. The ones which we call flat colours are already mixed with a clear coat, and are known as a single stage system, while other colours known as metallic require a separate clear coat; these are known as two stage systems.   The single stage system was often used on commercial vehicles in place of cellulose paint, helping the vehicle to look newer for longer.

Urethane paints are newer than enamels and more expensive, they are easier to apply much the same as the lacquer paints (cellulose), but are as tough as enamels.  This automotive paint requires three products, the colour, a reducer to thin the colour to the right viscosity for the spray gun and a catalyst used to accelerate the drying time.  Once the paint is mixed it needs to be used quickly, any unused paint must be thrown away.  Urethane automotive paint is toxic and you require a respirator when applying it.

Like enamel paint urethanes can be used alone or as multi stage paint.  As a rule of thumb, single flat colours are single stage, while metallic paints are two stage, often referred to as two pack paints.  The second stage is the application of a clear coat which gives an easy to paint, minimum work, and optimum results, which with a little care can look good for years.  Urethane clear coat is also purchased in three products, the clear coat, the reducer (thinner), and a catalyst (hardener).

Technology has brought us the newest form of automotive paint which is the water based paints.  These paints are the most versatile of all, are able to be applied to metal, primer or an existing paint job.  This paint is slightly different in the fact that urethane paint is mixed with a reducer, (thinner) which evaporates to dry the paint, so applying heat can speed up the operation.  Water based paints require a flow of air to best dry them, a bit like hanging out the washing on a windy day.  This induction of air takes some getting used to, as too much air makes the paint run, and too little takes an age to dry.

Nowadays a lot of high end makers of cars use water based paint such as BMW, but the downfall is that you still require a clear urethane coat to finish the process.

Out of all of the paints discussed in this article enamels is the preferred product for the American Motorhome (RV) up until just recently.   As late as 2004 when the fully painted bodies were preferred, was when urethane paint was used.  This process took a few years for the RV industry to get right.

The main failing was the last clear coat that was applied too sparingly gave a matt finish, or too much which gave an orange seal finish.  As time has passed, one of the finishes has been greatly improved, although one of the main problems that happened was the flaking of paint from the aluminium panelled vehicles.

Aluminium panels require a different primer called etch, this has an acid base which helps to adhere itself to the panel.  Normal primer does not have the ability to stick to aluminium’s, so once this bond fails it takes with it the coloured coat and the clear coat, leaving the bare aluminium.   As this failing of the primer takes place you can often see bubbles appearing.

For more information on paint please contact LAS Motorhomes on 01604 861999