Ford Fiesta (2011 year). Manual — part 166

Factory Paint Application

General fundamentals of paint
technology

Paint is a pigment-containing liquid which
undergoes chemical and/or physical processes
after it has been applied to a surface, so changing
into a solid film covering.

Repair paint consists of binder, pigments, filler and
solvent.

NOTE: Organic solvent is being replaced by
solvent based on water.

Constituents of paint

• Binder

– Mostly semi-fluid resins which bind together

the other components of the paint when it
dries.

– Makes the paint durable.

– Ensures good surface coverage.

• Pigments

– Fine, colored powders, which give color to

the paint.

– Cover the components below (covering

power).

• Additives

– Additives give the paint special properties.

– e.g. flow improver, softener, drying

accelerator, thickener.

• Solvent

– Thins the paint and allows it to flow more

freely.

– Evaporates during drying.

Painting process and corrosion
protection.

In production, painting consists of individual steps
which are optimally matched to each other.

Bodywork consists almost entirely of steel panels
which have been pre-coated with zinc. The zinc
layer is between 5-10 µm thick and acts as the first
corrosion protection layer of the steel panel.

Production sequence:

• Clean and de-grease

– In the first step, the bare bodywork is initially

dipped in a cleaning bath and cleaned with
a degreasing solution.

• Phosphatising

– The cleaned bodywork is dipped in a bath

containing various phosphate salt solutions.
This creates a crystalline metal-phosphate
layer which offers the optimal prepared
surface and also corrosion protection.

• CDP base

– The cataphoretic dip paint (CDP) base acts

as a further corrosion protection layer.

– In this process the bodywork is completely

immersed in a bath consisting of a paint and
electrolyte solution.

– By application of an electric voltage, an

electric field is created.

– Positively charged paint particles settle on

the negatively charged bodywork and form
a protective layer up to 20 µm thick.

– Next the bodywork is placed in a dryer, where

the CDP base is hardened at 180°C.

• Sealing, stone-chip protection

– Edges, seams and but joints are sealer with

a sealing compound.

– Vulnerable areas are coated with stone-chip

protection.

• Filler

– Filler protects the body panels from stone

impacts. Furthermore, any unevenness of
the metal surface is flattened out, in order to
create the most homogenous and fault-free
undersurface possible.

– Once the filler is dry, it serves as the base

on which paint is applied.

• Top coat

– The top coat is applied as a single layer or

two layers of paint.

– When working with two layer paint, in the first

job step the initial colored base paint is
applied. In the second job step, a clear
lacquer is applied, giving the base paint shine
and hardness.

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The structure of an original paint finish

During construction of the original paint, a total
surface thickness of between 120 and 130 µm is
achieved. The thicknesses of the layers may vary
however, because they are greater for horizontal
surfaces than vertical ones.

Paint layers

Description

Item

Steel panel

1

Phosphate layer 2.9 g/m², corresponding
to 2 µm.

2

Cathodic dip paint 30-35 µm

3

Filler 30-35 µm

4

Base paint 15-20 µm

5

Clear varnish 55 µm

6

Colored fillers applied in production

Filler which gives color is used in production. Its
use makes the base paint and clear varnish
unnecessary on certain vehicle interior surfaces
(engine, doors).

Not every exterior paint has its own matching filler.
It is more that the tones of the filler are color
compatible, i.e. they have similar intensity to the
top coat.

During repair painting the filler color tones must be
used according to the manufacturer's instructions.

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Paintwork Defects and Damage

Diagnosis and Damage Assessment

Paint concerns, regardless of their causes, are part
of the everyday work in the paint shop. Correct
damage assessment and determination of the
cause are preconditions for a professional
resolution of a paint concern.

Paint concerns can still occur through a variety of
causes, despite improved paint materials and new
spray methods.

NOTE: A first appraisal of the paint damage should
be done before cleaning. External factors such as
rust, droppings, incorrect or insufficient paint care
can then be more easily detected.

Diagnosis is best done in daylight but not in direct
sunlight. Exact evaluation can also be done under
artificial light from special luminescent lamps.

Paint damage guide

The most important paint damage concerns which
make a paint repair necessary are:

• Damage from biological paint contamination

such as bird or insect droppings, tree resin and
aphids.

• Chemical paint damage caused by industrial

contaminants such as smoke, fuel, acids, oils.

• Mechanical damage caused by stone impact

during operation, scratches in the car wash and
parking.

• Damage caused by faults in treatment.

Application defects such as paint runs or orange
peel.

• Dirt inclusions in the paint layer, e.g. caused by

dust in top coat or textile lint.

• Damage due to corrosion.

Before repair of such paint concerns, exact
diagnosis must be performed to determine the
cause exactly. On the spot diagnoses using simple
aids and processes are often enough.

Diagnosis without disturbing the paint is done by:

• Optical inspection without visual aids, under

suitable light conditions from a suitable angle
and correct distance.

• Optical inspection with the help of a magnifying

glass.

• pH paper.

• Measurement of the thickness using FE / NFE

coating thickness meters for ferrous (FE) and
non-ferrous metals and non-magnetic steel
(NFE) - magnetic process on steel panels, eddy
current process on non-metals.

A test method where the traces of testing can be
easily removed again is the finger nail test. With
suitable experience the existing hardness of the
paint can be determined.

Test methods where the paint is partially destroyed
are:

• Pencil hardness test.

• Adhesion test using adhesive tape.

• Lattice cut test process to check the strength of

adhesion.

Under certain circumstances these test methods
are not enough for a certain diagnosis. In this case,
paint diagnosis under laboratory conditions must
be performed.

Measuring and testing equipment for
painted surfaces

Coating thickness measuring devices

Magnifying glass

pH paper (together with water)

Suitable photographic equipment with macro lens

Shine measuring equipment

Paint damage caused by environmental
factors

• Bee droppings

• Bird droppings

• Insects

• Tree resin and sap

• Aphid secretions

• Tar spots

• Cement, plaster and slaked lime

• Rust film/deposits from industrial fallout

• Battery acid

• Brake fluid

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In all the cases of paint damage described
below, if the damage is irreversible a new paint
finish must be applied.

Paint damage cause by bee droppings

Bee droppings can be recognized on a paint
surface through its yellow or brown color and
sausage or drop-like shape with a diameter of 3-4
mm.

Cause/damage pattern:

• In combination with heat and high air humidity,

bee droppings leave discolorations and cause
paint decomposition.

• The paint can be destroyed down to the filler.

Repair of damage:

• If the damage is light, perform a polishing repair.

Paint damage caused by bird droppings

Bird dropping damage appears most often as matt,
etched topcoat areas of various sizes. If left on the
vehicle for a long time, crack formation and etching
down to the filler will occur.

Cause/damage pattern:

• Bird droppings are particularly harmful in

combination with heat and moisture. The urea
(white part) has a very high salt content and is
very aggressive.

• The intensity of the damage varies depending

on the type, quantity, contact time and extent.

• Cracks, etching, marks up to dissolution of the

top coat are the results.

Repair of damage:

• If the damage is light, perform a polishing repair.

Paint damage caused by insects

At insect impact locations on the hood, roof and
bumper, small etched or etched through paint
marks with partially visible spots of filler.

Cause/damage pattern:

• The top coat layer is destroyed in a short time

by surface swelling and etching.

• Colliding insects stick to the paint surface. In

combination with moisture and heat, because
of the resulting acids the insect bodies sink into
the paint top coat.

• The corrosion is G, C, U or O shaped and is

only a few millimeters thick.

Repair of damage:

• Wash the vehicle, treat the affected area with

insect remover. Clean the paint surface several
times.

• Protect with hard wax.

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