Ford Fiesta (2011 year). Manual — part 171

• Tools with a rigid backing pad do not adjust to

fit the surface. They are used for flat surfaces.

• Tools with a flexible backing pad are used for

fine sanding of a surface because they adjust
to the shape of the surface.

• Build up an even working pressure over the

sanding surface.

• Keep the sanding paper tight on the tool (use

self-gripping systems).

• Align the extraction holes in the sanding paper

with the holes in the tool.

• Guide the tool flat over the surface to be worked.

Do not tilt it.

Hand sanding can be carried out dry but also wet.
Wet and dry paper with particle size P 80 to P 1200
is used for this in the paint field.

Ways of sanding

Sanding tools are driven either by electricity or
compressed air.

Description

Item

Sanding machine

1

Polishing machine

2

Orbital sander

3

The disadvantage of electrically driven machines
is that their own weight is high compared with
pneumatic systems. They also become warm
during work. They do not however need any special
operating equipment for their energy supply.

Sanding machines are categorized by their type of
sanding movement.

Rotational sanders

On these machines the sanding paper turns.

• Advantage:

– Ideal for heavy sanding work.

– Fast and aggressive sanding possible.

• Disadvantage:

– Large amount of heat developed.

– Difficulty sanding flat surfaces.

• Application:

– Removal of old paint layers.

– Preparation of panel for stopper.

– Removal of rust.

Oscillating sander

On these machines the sanding paper oscillates.
The backing pad is rectangular.

• Advantage:

– Large sanding surface.

– Ideal for large and flat surfaces.

• Disadvantage:

– Hardly useable on rounded surfaces.

– Flexible backing pad not possible.

– Vibrations because of the poor support of the

backing pad.

• Application:

– Sanding of polyester stopper.

– Sanding processes on flat surfaces.

Orbital sander

On these machines the sanding paper turns and
oscillates.

• Advantage:

– Easy to handle and good sanding power.

– Minimal heat development.

• Disadvantage:

– Not suitable for sanding stopper on flat

surfaces.

– Smooth guidance important, otherwise

sanding marks will occur.

• Application:

– Sanding of paint layers.

– Well suited for final preparation of a primer.

NOTE: Comply with the manufacturer's
recommendations when setting the orbital sander.

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On the orbital sander, stroke settings of approx. 3
mm for fine sanding work and approx. 5 - 7 mm for
coarse sanding work have been established.

Polishing and finishing tools

The term polishing in the context of paint repairs
means the elimination of paint flaws and high shine
polishing of neighboring parts.

During polishing the fine sanded surface is returned
to a high shine using a special abrasive polish.

Before the actual polishing, all flaws in the paint
surface must be removed and the following working
procedures must be adhered to:

• Thoroughly clean the vehicle.

• Remove spray mist from all surfaces.

• Sand out and polish particle inclusions.

• Sand down paint runs and polish them out.

• Examine the exactness of the color match in

daylight.

• Remove masking edges.

• Remove sanding water, sanding dust and polish

residues.

After the polishing process the results must be
tested using a special test spray.

Infrared drying technology

The drying process in a painting/drying cabin
occurs through heat conductance (convection).
When an infrared dryer is used, the drying process
is through heat radiation.

The infrared rays penetrate the air and the paint
layer without warming them. Because the infrared
rays are reflected from the steel panel, the paint
coat is warmed from the inside outwards.

Advantages of infrared drying:

• The drying process occurs from the inside to

the outside.

• The drying time is shorter than for warm air

systems.

• Because the infrared dryer consists of several

cassettes which can be switched on
independently, the drying area can be optimally
controlled.

Independent of the manufacturer's instructions,
pay attention to the following:

• Flash-off time of the paint before switching on

the infrared dryer.

• Distance between the infrared dryer and the

surface.

• Duration of the irradiation.

The most common use of the infrared dryer is to
dry stopper and primers. The wait time between
the job steps is shortened without having to use
the painting/drying cabin.

The painting/drying cabin can then be used
exclusively for application and drying of topcoat.

There are two types of infrared dryer:

• Infrared dryer with short wavelength radiation.

• Infrared dryer with medium wavelength

radiation.

As an indication, the following drying times are
listed for some materials (at 80 cm distance):

NOTE: Observe the material manufacturer's and
supplier's specifications.

• Polyester stopper 2 minutes.

• Spray stopper 2 to 7 minutes.

• Water based primer-filler 7 to 9 minutes.

• Primer 3 to 8 minutes.

• Top coat 7 to 10 minutes.

Air dryers

The air dryer is suitable in places where drying
needs to be done, but without great outlay
(painting/drying cabin or infrared dryer).

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NOTE: Air from the compressor is often too cold
for effective drying.

Air dryers use the venturi effect to blow the warm
ambient air over the paint surface in a gentle air
flow.

Paint mixing system

Because of the many different color variants, it is
now seldom possible to store all color shades as
ready-made mixtures.

For this reason, vehicle manufacturers make the
mixture proportions of their paints available as color
codes. The required color shade can be obtained
from the paint mixing system using this color code.

All the color components are combined according
to their proportions by weight using a precise
computer scales to produce a finished color shade.

Painting cabin

The air requirement in a painting cabin is large.
The outside air which is drawn in must be passed
through filtering and warming equipment. This
particularly applies during colder times of the year
and especially for combined types of building where
the painting cabin is also used as a drying cabin.

It is primarily used to keep the air free of dust. At
the same time, explosive solvent-air mixture
concentrations are prevented

NOTE: Vacuum will lead to contamination of the
newly applied paint. The outside air flows through
door gaps, wall joints and other openings and as
it does so, brings dust deposits with it.

The air supply quantity depends on the size of the
painting space and the quantity of extracted air.
Enough air must be supplied to cause positive
pressure in the painting space. An air extraction :
air supply ratio of about 1 : 1.05 is sufficient.

The filters should have a dust-removal grade of
not less than 99.8% and must always be kept
clean.

It is especially important that the air supply does
not cause strong air currents in the painting cabin.
If not, the following problems could occur:

• Paint contamination cause by paint mist, which

persists in air eddies and gradually falls on the
fresh paintwork.

• Flow problems in the paint because of the high

speed of the air, causing the paint to thicken
very quickly on the surface.

• Loss of gloss and wrinkle formation because

the surface dries too fast.

• Painter disturbance while working.

In modern paint cabins the air supply is provided
from the complete surface of the ceiling. The air
speed should be 0.3 m/sec (measured in the
unrestricted cross-section of the spray cabin). At
the same time, the air in the cabin should change

Air extraction is best achieved through extraction
channels in the floor of the painting cabin.

NOTE: Refer to the manufacturer's specifications
for the operating instructions, safety instructions
and notes on the maintenance of a paint cabin.

Smooth walls in the paint cabin should prevent
dust deposits. Regular cleaning is necessary
however.

Special easily washed adhesive-bonding paint can
be applied to the walls to protect the cabin from
paint mist.

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about 350 times per hour.

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Refinishing Materials

The manufacturer's instructions must always
be followed when dealing with all materials!
The information given in the following text is data
which is independent of the manufacturer, and it
should only be used as an indication.

Stopper materials

• 1-component nitro-combination stopper

• 2-component polyester stopper

• 2-component plastic stopper

Use suitable primer to protect from corrosion areas
which have been sanded bare before applying
stopper.

1-component nitro-combination stopper

Nitro-combination stopper has mostly been
superseded by 2-component polyester stopper.

Fast drying fine stopper for the smoothing of
irregularities.

The working properties of 1-component
nitro-combination stopper can be improved by the
addition of nitro thinners.

Drying time increases with thickness of the layer.

1-component nitro-

combination stopper

Application

Max. 80 µm

Layer thickness

up to 2 hours at 20°C

Drying time

P240 - P400

Sand

2-component polyester general stopper

CAUTIONS:

Do not exceed the quantity of hardener
specified by the manufacturer, excess
peroxide can cause staining of the paint
top coat.

Mix the stopper base and the hardener well
to avoid a marble-like effect.

Check that the manufacturer permits use on the
substrate to which it will be applied.

2-component polyester stopper is available in
coarse and fine grades. The coarse stopper can

be used for very uneven areas and surfaces and
fine stopper or spray stopper should be applied
afterwards.

2-component polyester

coarse stopper

Application

Rough equalization of

unevenness

Use

approx. 3 - 5%

Hardener quantity

approx. 4 - 6 minutes

Working time

20°C approx. 12 minutes

Drying

Short wavelength infrared

approx. 4 minutes

Medium wavelength

infrared approx. 5 - 10

minutes

Eccentric, sanding disk

by hand

Sanding tool

P80 - P150

Grade

2-component polyester

fine stopper

Application

Equalization of uneven-

ness

Use

approx. 3 - 5%

Hardener quantity

approx. 4 - 6 minutes

Working time

20°C approx. 12 minutes

Drying

Short wavelength infrared

approx. 4 minutes

Medium wavelength

infrared approx. 5 - 10

minutes

Eccentric, sanding disk

by hand

Sanding tool

P80 - P240

Grade

2-component polyester

glass fiber stopper

Application

Equalization of uneven-

ness; blending in of

vehicle extensions; repair

of GRP components

Use

approx. 3 - 5%

Hardener quantity

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