There
is a plethora of information available on the various abrasive compounds, chemical
cleaning fluids and paint protection products that can be applied, but understanding the paint itself seems
critical to detailing excellence.
The Basics
All
paints are made up of three ingredients: binder, pigment, and a carrier agent.
Pigment, or tint, is self-explanatory-it's the colour you see. Binder is often
referred to as resin, and it can be helpful to think of it like tree sap, that
thick, sticky hydrocarbon liquid that hardens when exposed to air. And carrier
agent refers to the solution (water or solvent) that the resin is suspended in.
It keeps the binder in liquid form until it is applied, at which time it either
evaporates or chemically bonds to the surface of the car.
In
general, urethane and enamel refer to the chemistry of the hydrocarbon polymers
that form the resin (binder) of the paint. And that chemistry affects the look
and durability of the finish, how it is sprayed on the car. Most new cars are
painted with a type of urethane, and most collision repair shops use urethane
to repair damage.
OEM
Finishes
Consistent quality and the most durable paint finish coatings
available to consumers are produced at the OEM level. These coatings comply
with the vehicle manufacturer’s specifications and quality controls and are
applied in a controlled environment, using quality materials and highly
specialized application equipment. Also, the prefabricated metal used for body
panels will never be cleaner and in better condition than when it’s used to
manufacture new products. The longer the original factory coating lasts, the
higher its value to the owner.
Most popular vehicle
colours
1. White-22%
2. Silver-20%
3. Black-19%
4. Red-9%
5. Blue-7%
6. Green-2%
Automotive
Coating
[: any
liquid, liquefiable, or mastic composition which after application to a
substrate in a thin layer is converted to an opaque solid film]
Paint is a liquid, usually comprising 30 to 40% solids and 60 to
70% liquid. As it dries it becomes a solid and a gas (the solvent) that
evaporates, leaving behind the solid. The three primary type of ingredients
found in most paint type coatings are –
1.
Binder (film former)
2.
Carrier (solvent)
3.
Solutes (pigment)
The binder is the film-forming component of paint, it imparts
properties such as gloss, durability, flexibility, and toughness. Many binders are too thick to be applied and
must be thinned. The thinner is also called the carrier, because it makes it
possible to transfer the binder to the surface. The pigment provides the paint
with colour. All paints consist of a solids portion, essentially comprised of
the pigments and binder, and a liquid portion. After the liquid portion
evaporates and a coating dries, it is the solids that remain on the surface. Some
paints form by solvent evaporation only, but most rely on cross-linking
processes
Surfactants are added to stabilize the paint so that it will not
separate, settle or become too thick to use. They also keep pigments dispersed
for maximum gloss and hiding; and they help “wet” the surface being painted so
the paint won’t “crawl” when it is applied. Surfactants also provide
compatibility between tinting colorants and bases so that the correct colour
will be obtained.
Urethane paint was first created in the mid-1960s, utilizing the
newly-developed plastics technology of that era, to be superior to enamel paint
in terms of durability. It also has the advantage of being a surface that can
be applied over enamel if the enamel-painted surface is prepared first. A
urethane painted surfaces is minimally affected by ultraviolet rays, making the
paint a good choice for outdoor surfaces.
It is widely used in the automotive industry because of its
durability. Inexpensive urethane paint might contain less than 10 percent
polyurethane. High-quality polyurethane paint has a higher percentage of the
expensive polyurethane ingredient.
A urethane-painted surface can be expected to
contract and shrink over time.
Polyurethane (PUR and PU) is polymer composed of a chain of
organic units joined by carbamate (urethane) links. Polyurethane polymers are
formed by combining two bi- or higher functional monomers. One contains two or
more Isocyanate functional groups and the other contains two or more hydroxyl groups.
Approximately 30% of OEM body panels are coated with a scratch
resistant clear coat and 70% are coated with traditional clear coats. When
scratch-resistant clear coat systems were developed, conventional polishes were
unable to eliminate the sanding defect. Menzerna took the lead in designing an
innovative new polishing system that was successful on scratch-resistant clear
coats while achieving even higher levels of surface quality and gloss.
The highest quality, longest lasting surface coatings available
to consumers are the finishes produced at the factory. Factory coatings are
applied in a controlled environment, using quality materials and highly
specialized application equipment. Also, the prefabricated metal will never be
cleaner and in better condition than when it’s used to manufacture new
products. The longer the original factory coating lasts, the higher its value
to the asset and the owner.
Finish quality is the primary attraction for new customers, but
durability is also important. For this reason, many manufacturers go to great
lengths to prevent the conditions that cause new coatings to fail prematurely.
This involves critical surface preparation, rust inhibitive pre-treatment, and
state-of-the art base coat/clear coat paint systems. The integrity of the
original application allows responsible owners to provide a significant
increase in service life through proactive maintenance.
Among the inorganic pigments, TiO2TiO2 white is, by far,
the most important one. The photo catalytic activity of TiO2TiO2 leads to
a rapid degradation of the organic binder matrix, so the surface of the TiO2
particles has to be covered by an inorganic coating to prevent the matrix
from being photo oxidized. This is done by applying layers of SiO2 and
Al2O3
Automotive
Paint Systems
Paint, a common polymer coating, is used to change the colour,
change the reflectance (gloss), as well as forming a protective coating. The
structure of paint consists of pigments in a matrix of resin; colour is
determined by light-reflecting chemical particles (pigments) in the paint.
The paint on every vehicle is different; dense (hard) less dense
(soft) etc. even if they are the same colour, year, make and model, so take
that into consideration when you are detailing.
Worldwide, approximately 80% of all passenger cars are coated
with 1K clear coats and the remainder with 2K clear coats. The 1K clear coats
are subdivided into solvent-based (solvent
borne) acrylic melamine systems; clear coats with enhanced surface etch
resistance, high solid-systems, water-based (waterborne) systems and powder versions. The 2K clear coats include solvent-based,
super high-solids and water-based versions.
A paint resin system comprises a binder, which as its name
implies holds the paint molecules and various other components (additives}
together and a film former, which creates a dense surface. Various solvents are
used, one as a carrier system, one holds the paint together and the final
solvent that evens out the paint to create a smooth, glossy surface (this solvent
has the most bearing on the ripple effect (orange peel). These solvents are
responsible for the paints density (hard or soft) the paint becomes
Basecoat
/ Colour Coat Formula
·
Petroleum –Based Solvents - 40-60%
·
Resins and Binders - 30-50%
·
Pigments & Colorants - 5-10%
·
Silicone Polymers & Other Additives (Catalysts, etc.) - 1-2%
A clear coat / colour coat system consists of one or more primer
layers, a flat colour layer and a glossy, clear top layer. The primer is a corrosion inhibitor and a
bonding agent for the bare metal and the colour layer. It prevents corrosion and provides a stable
substrate for the colour and clear coats.
The colour layer is applied to the primer and is typically very
thin. Its only purpose is to provide
colour. The clear coat is two to three
times the thickness of the colour layer, adding to the appearance of paint
depth and offering additional protection.
Many luxury car manufacturers also use ultraviolet-light-blocking
technology in their clear coat systems for protection against sun fading.
Clear
coat 2K Formula
· Petroleum –Based Solvents - 20-40%
·
Resins and Binders - 50-70%
·
UV Absorbers - 1-2%
·
Silicone Polymers & Other Additives (Catalysts, etc.) - 1-2%
·
Isocyanate hardener and catalyst: 0 -2%
E-Coat (Electro coat)
In order to
achieve maximum coverage and therefore maximum corrosion resistance, this first
coating layer is applied in a process known as electro deposition. The
metal body is electrically charged, then immersed in a bath containing
oppositely charged paint particles. These particles are attracted to the
metal surface, neutralized, and can then be baked into a coherent, tough
film. E-Coat is very sensitive to ultra violet (UV) exposure and if
allowed, will exhibit a "powdery" surface as it breaks down, and is
no longer able to protect the metal surface from corrosion.
Current
practice favours making the vehicle body the cathode in this process (this
minimizes corrosion for steel). These products are called cathode electro
coats. A new environmental requirement requires that the electro coats must
function without the addition of heavy metals such as lead and in some areas in
Europe also without tin.
Primer
The primer
layer is the coating layer that joins a corrosion-protected substrate to the
topcoat. It functions to smooth out
surface irregularities, improve stone-chip performance, and helps to protect
the substrate from visible and UV light.
Today’s primers include both solvent and water-based. Colour-keyed primers are often used to allow
minimum basecoat film thickness, to optimize the painting process and to
minimize defects related to stone-chip damage
Basecoat
The basecoat
is either solvent or water-based and this coating layer provides colour and
aesthetic effects. Modern requirements
for vehicles aesthetics often require micas, aluminium flakes and other effect
pigmentation. These can be incorporated
in one basecoat layer or in a separate layer (for example in two-tones).
If two basecoat layers are used, the sandwich
with the clear coat is called a tri-coat topcoat. DuPont Automotive Systems is
the world leader in wet-on-wet tri-coat application in both solvent and
water-based basecoat topcoats.
Clear coat
The clear
coat is the coating layer that forms the last interface to the environment. It carries the biggest part of the
technological performance and must be able to resist environmental etch, bird
droppings, car wash machines and other outside influences.
To improve
performance against all these influences, OEM coating systems move from colour
topcoats to basecoat/clear coat (BC_CC) systems. The clear coat in combination with the
basecoat forms the automotive topcoat, which gives the vehicle its aesthetic
colour appearance. One and two component
clear coats (1K and 2K) are applied over both solvent and water-based basecoats
Clear coat
paint was originally formulated to protect the base coat from ultra violet (UV)
radiation damage. Once vehicle mfg. started to use metallic paint a clear coat
was necessary to cover the metallic flakes that are subject to oxidation.
Based upon
the studies of PPG, DuPont, BASF and Sherwin Williams, the average vehicle's
paint system will absorb up to a pint of water into the substrate when
subjected to rain or car washing
Based on DuPont Automotive
Paint Systems
Typical
OEM Paint Thickness
·
E-Coat
33 µ (1.3 Mil) - an
anticorrosion coat applied to both sides of the steel to prevent corrosion
·
Primer
18 µ (0.7 mil) - Initial
protection layer with texture to assist the pigment layer in bonding to the
metal beneath
·
Base
Coat 15 µ (0.6 mil) - The
basecoat is usually 0.5 to 1 mil thick
·
Clear
Coat 48 µ (1.9 mil) - The
clear coat provides gloss plus physical protection from the elements, including
ultraviolet rays
All paint has three major components: a pigment for colour and
hiding powder; a binder that holds the pigment to the surface; and a carrier to
maintain the pigment and binder in liquid form.
Current
Information
To
be of real practical use, a subject like automotive detailing requires a great
deal of research, and updating as new products become available. The advent of
materials like detailing clay, micro fibre technologies and finely milled micro
diminishing abrasives, suitable for ceramic nanotechnology paints are examples
of why it’s so important to monitor the industries new products, chemical
technologies and ideas that are constantly being introduced, as are the
techniques for applying them, hence all of the in-depth articles will be
up-dated and revised on a regular basis
Always
be willing to learn; because the more you learn, the more you’ll realize what
you don’t know. It is
said that knowledge is power, with the caveat that it includes access to a
reliable information sources. I would
like to think that these articles become an asset to anyone who is new to
detailing and to professional’s alike, as well as industry experts who seek to
advance their knowledge.
I
hope these articles are informative. They are based on the current status of
technical development as well as my experience with the products.
By
having some understanding of the ‘What’ and ‘Why’ as well as the ‘How’ along
with a little science to help you understand how the chemicals we use react,
you can achieve the results you desire.
I would appreciate it if you
would share these articles as it helps other detailers further their knowledge.
As always if you have
questions, I’ll do my best to answer; bear in mind the only stupid questions is
the one that was unasked. Questions and/ or constructive comments are
always appreciated
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