Properties of Car Paints
The quality of car paint is defined by the properties of denseness, adhesiveness, hardness, and elasticity. High-quality painting extends a car’s lifespan by preventing corrosion and improves its resale value by providing aesthetics and uniqueness to its appearance.
What Goes Into Car Paint?
Automotive paint comprises a pigment, binder, filming agent, filler, solvent, additives, and special pigments.
Pigments give paints their tone and colour, their purpose being decorative and to provide the film with covering capacity. They also make the coating stronger, and some even prevent corrosion. Pigments may be natural or artificial oxides, metal salts or powders, or organic materials. Transparent car varnishes contain no pigments.
A binder, an integral component of paint, gives it the quality of adhesion to the painted surface. It holds the colouring pigment and forms a smooth glossy surface after painting.
Filming agents may be natural or synthetic resins or vegetable oils. Since they are typically highly viscous, adding solvents helps reduce their viscosity. Some paints may consist of more than one filming agent.
Solvents are organic liquids, including hydrocarbons, ketones, alcohols, ethers or their mixtures, that keep paints in liquid form during manufacturing and storage and allow uniform application. Solvents evaporate when the paint is applied, leaving the pigment and binder in the mixture. Powder coatings may not contain solvents.
Fillers, usually inexpensive white or lightly coloured natural mineral powders, such as talc, gypsum, mica, kaolin, and chalk, lend to a paint’s final volume and density. Some, such as mica or asbestos, may enhance the paint's heat resistance.
Target additives enhance product properties, such as coating elasticity, resistance to ageing, fire resistance, and ease of bottling. Additives such as drying accelerators, plasticisers, and matting and structuring additives are typically added to the paint just before use.
Special pigments create metallic, nacre and chameleon finishes. Aluminium powder pigments infused into solid colours creates depth and makes the metallic paint shimmer. Another special pigment, one that reflects sunlight dependent on where it is located in the coloured layer, gives car paints their nacre or glossy or even-three layered look. Colour-shifting pigments create the chameleon or pearlescent look that changes according to the angle one looks at them.
Types of Car Paint Finishes (Just to Start You Off!)
The solid paint finish, consisting of three layers, the primer, the paint, and the lacquer protection that also provides a reflective shine, is common and typically free of additional cost, at least on the few basic colours, as it is cheap to produce and easy to install. Exotic colours may demand some extra payment on new cars. Minor scratches and nicks can be fixed using DIY kits and may not warrant a visit to an auto body shop. Matching shades is usually possible if a panel must be resprayed.
The metallic paint finish is more reflective and eye-catching, even in dull lighting, due to the small amounts of aluminium powder mixed into solid colours, and offers a more extensive selection of colours. While metallic paints camouflage imperfections easily, fixing just a scratch will require professional services, and colour matching can be complex. Performance-oriented cars often receive a metallic paint finish.
The matte paint finish may look stylish but requires high maintenance in terms of cleaning and repair work despite its protective layers. For instance, bird droppings, acidic in nature, can eat away the epoxy coat. The matte finish is also mostly limited to a few shades, such as silver or black. It may even be applied as a removable vinyl wrap.
The pearlescent paint finish, created by adding ceramic crystals that reflect and refract light, typically warrants an additional cost for its unique appearance, although the colour selections may be limited. Its advantages are durability, value addition upon resale, and the ability of high-end auto body shops to deliver a customised finish with depth.
Urethane finishes, with an extensive colour range, mixing capabilities, and resistance to UV damage, are popular commercial options. The ease of colour-matching urethane paint allows touch-ups or partial resprays needed due to fading caused by the sun. Urethane finishes are also quick to dry and highly sturdy due to the use of hardeners. However, the hardener being toxic, leftover mixed paint must be used or disposed of rapidly. Car Painters must sport safety gear while using any paint but respirators and goggles are especially critical when using urethane paints to prevent exposure to toxic fumes.
The Spectrum of Paint Coats and Layers
Primers, mostly in shades of grey and black, are the prep or undercoat finish. They are the binding layer that helps the paint adhere to the surface of a car. A base or clear coat on a metallic surface without the primer would look untidy, and its inconsistent bonding would also cause flaking and chipping. Spray paint primers help keep bare metal surfaces moisture-free and thereby avoid oxidation on rust. Due to its porous character, the primer requires sanding to create a flat surface and avoid a bumpy second coat or one that does not adhere well.
Base coats are the raw coloured paints that go on the primer. However, since they do not contain strengtheners or hardeners, they cannot adequately protect themselves or the premier layer and metal frame. If it is left raw, the paint will show up blemishes and let in moisture, leading to a rusty frame surface.
Clear coats are free of colour or pigment and go on top of base coats. They help protect the base coat, primer, and frame while adding to the shine. The UV inhibitors present in them prevent oxidation and fading due to the sun’s UV rays. They may also contain specialised chemicals that help them adhere to flexible parts, such as plastic bumpers. Further, being made of urethane or polyurethane, they make cars look shiny, a look that can last for years. Given the twin merits of gloss and protection, layering a primer, base coat, and clear coat is the most common methodology for painting cars.
Acrylic lacquers are outdated for use on modern cars and need considerable handwork. However, they are still relevant for classic or antique cars or showroom vehicles, which can afford a glaring shine because they are not meant to be driven around daily and therefore do not need as much protection as a frequently-used car. Or else it would cost one dearly to maintain the shine. Mixing the thick, glue-like lacquer paints with a thinner makes spraying easier.
Enamel paints could be synthetic or acrylic. They are typically available only in basic premixed colours and used where durability is not critical. Synthetic enamels are single-stage paints that need no hardeners or baking. Acrylic enamels use hardeners to boost durability and reduce drying time and may be available as single-stage or two-stage paints that may need baking. While premixed colours are the norm, it is possible to match your car’s colour by getting acrylic enamel paints mixed.
Chameleon paints are rare and give the illusion of changing colours when the car is viewed from different angles.
Powder coatings bake a sort of plastic dust onto metal with a static charge. They are used on small parts and areas that need a sturdy finish, such as wheels.
Underbody paints, which can be either brushed or sprayed, are moisture-resistant, protect against impact from stone chips, and help absorb sound.
The Topography of Topcoats
The single-coat or single-stage topcoat, also known as monocoat and direct gloss, blends all the required components, including colour, gloss level, chemical-mechanical and UV resistance, providing appearance and protection. It has the merits of quick application, hardness and cost-effectiveness. However, its chemical resistance is low, and it offers a limited range of colours.
The two-coat topcoat consists of a first coat that gives the colour and effects and the second coat that is responsible for sheen and protection in terms of mechanical and chemical resistance. Its merits include standardised, quick and cost-effective application in a range of solid, metallic and pearlescent finishes, even offering special effects.
The three-coat topcoat comprises a coloured base, a special effect transparent intermediate coat which lets light pass through and reflect it, and a clear coat. Its merits are its unique and bright colour range, effects and reflection. However, it is expensive and difficult to match if it needs refinishing.
Solving the Topcoat Mystery
While experience can help a professional Car Painter use their visual expertise to differentiate between various finishes, judging the type of topcoat in this manner can lead to errors. Sanding may reveal a single topcoat if the dust is coloured. However, if it is whitish, it is hard to tell if the topcoat is a two-coat or three-coat. That is why colour formulation carried out using a spectrophotometer yields precise results of the pigments present, thereby revealing the finish and the type of topcoat.
What is Flash-Off Time?
When a first coat applied on any material must be followed by another one, there is typically a necessary waiting time before recoating or spraying the second coat. This wait time is called the flash-off time, the time a solvent takes to evaporate. Too long a wait time leads to the need for scuffing. Too short a wait time can cause the solvent to dissolve the second coat, giving rise to irregularities in the first coat.
In general, one can expect atmospheric temperatures to generate a minimum flash-off time of 20 minutes. In addition to abiding by the precise recommended flash-off time, achieving a perfect coat requires the correct viscosity, a spray gun that works at the recommended air pressure, and a catalyst in the base coat.
Some Equipment & Materials Needed by a Car Painter
- A power sander & sanding pads
- An air compressor
- A paint sprayer/spraying gun
- Sandpaper with the recommended grit
- A cleaning solvent
- Primer
- Enamel, acrylic enamel, or polyurethane paint
- Undercoat/primer
- A clear coat lacquer
- Paint thinner
- Safety gear (face mask, respirator, goggles)
- Masking tape
- Newspaper and a rag
- Denatured alcohol or mineral spirits
- Rubbing compound (optional)
Automation in the Automobile Body Repair Industry
Car Painters must adapt to working with robots that paint cars as their usage grows in the auto body repair industry. Auto body painters may ensure that they keep in sync with current business and technology trends in the business by learning how to use the latest tools and techniques.
The Value of Customer Satisfaction
The automotive industry greatly values customer satisfaction. It aims to provide the customised buying experience that clients seek, which includes the fulfilment of individual requirements. Car Painters are crucial in pleasing customers by adapting to their requests for specific colours and finishes and fixing minor dents and scratches to make their cars as good as new or unique.
Increased Emphasis on Environmentally Friendly Practices
Businesses are increasingly focusing on environmentally-friendly operations as environmental awareness grows worldwide. The trend particularly applies to the auto body painting sector, where the need is strong to produce and use environmentally safe paints and coatings. Car Painters may play a significant role by learning about ecologically friendly paints and coatings and encouraging their customers to make informed choices.
Potential Pros & Cons of Freelancing vs Full-Time Employment
Freelancing Car Painters have more flexible work schedules and locations. They have full ownership of the business and can select their projects and clients. However, they experience inconsistent work and cash flow, which means more responsibility, effort and risk.
On the other hand, a full-time Car Painter has company-sponsored health benefits, insurance, and retirement plans. They have job security with a fixed, reliable source of income and guidance from their bosses. Yet, they may experience boredom due to a lack of flexibility, ownership, and variety.
When deciding between freelancing or being a full-time employee, consider the pros and cons to see what works best for you.