Preparation by using paint

Remover

If the existing paintwork is in poor condition, or if

the damaged area is so extensive that the remaining

paintwork on the damaged panel is not worth rubbing

down, the existing finish can be removed with

paint remover. The first task is to remove any

flashes or chrome strips that can easily be removed.

If the work is being carried out in a shop where several

vehicles are being refinished, it is advisable to

store these fittings in boxes which should be

Figure 17.48Festo dust extractor (Minden Industrial

Ltd )

Figure 17.49Air driven polisher with foam pad

(Desoutter Automotive Ltd )

Automotive finishing and refinishing 601

labelled with details of the car such as customer’s

name, registration number and type of car. On a

complete refinishing job it is also advisable to label

each part to indicate from which side of the vehicle

it was removed. Should it prove to be too difficult

or impractical to remove any parts, these should be

masked completely. Though it is not always necessary

to mask the surrounding areas when stripping,

it is advisable to do so because if any paint remover

accidentally came into contact with an adjoining

door or bonnet, damage to these areas would occur.

However, if masking paper is applied it should be

of a fairly stout nature and laid in two or three

thicknesses to ensure that any paint remover accidentally

deposited on it does not immediately penetrate

to the paintwork beneath.

Paint removers were formerly of a highly flammable

nature and constituted a fire risk, but

nowadays non-flammable types are available and are

widely used. As well as removing fire risks they also

evaporate at a much slower speed; hence they remain

wet for a longer period and so have better penetration

properties. Though they are quite easy to use, some

precautions should be taken when working with

these paint removers. They can be a cause of dermatitis

by penetrating the pores of the skin, dissolving

the natural oils beneath and so leaving the pores

open to attack by bacteria. A simple precaution is to

apply a barrier cream to the hands before commencing

paint stripping, and to rinse off with water any

remover which comes into contact with the skin.

Strong rubber gloves are very useful when using liquid

paint removers. The operator should not smoke

when using paint remover, even though it is not flammable,

as it gives off a strong vapour which, on coming

into contact with a naked light, becomes toxic in

nature. This toxic vapour if inhaled into the lungs

will cause dizziness, nausea, and even vomiting.

Adequate ventilation should be provided in any shop

where paint remover is used, for the same reasons.

A fairly liberal coat of stripper should be applied

to the surface and allowed sufficient time to penetrate

through the various layers of paint. The softened

paint is then removed with a stripping knife

and the surface washed down with a generous

quantity of water. Both the laying on and the washing

off of the stripper can be done with old or

cheap paint brushes. To assist the removal of paint

at awkward places, a wire brush is an invaluable

tool. Very often a layer of scum or a fine stain of

primer is left on the surface but this can be quite

easily removed with steel wool and water. It is

imperative that all traces of paint remover be thoroughly

rinsed off, otherwise it will cause damage

to any subsequent paint system applied to the job.

Preparation by using abrasive

Paper

Before the rubbing down of a local repair commences,

the whole panel should be thoroughly

washed down with a detergent to remove all traces of

wax polish. Nowadays nearly all wax polishes contain

silicones, which can create ‘pinholing’ in any

paint applied over them. Water miscible cleaning

solutions, which are normally used for degreasing,

are suitable for wax removal. Thorough rinsing with

water and drying should follow. The grade of wet-ordry

paper chosen to rub down the damaged area

depends very greatly on the degree of damage, but

normally 180 grade is suitable. The paper should be

folded and torn so that one-quarter of the length can

be removed (Figure 17.50). This is then attached to a

rubber rubbing block and the damaged area abraded

using a liberal quantity of water to keep the work

clean so that continual inspection can take place. The

rubbing down is normally carried out with a forward

and backward motion until the paint is removed and

a feather edge achieved. Should paint remain in

recessed areas, it can be removed with a wire brush,

coarse steel wool, or abrasive paper without the rubbing

block.

Figure 17.50Method of fixing abrasive paper into

rubbing block

As an alternative to rubbing down by hand, power

tools can be used to speed up the process. These can

be either electric or driven by compressed air. Those

which are electrically driven are used dry, but compressed

air tools can be used either wet or dry. The

latter types are generally favoured for lighter work

where damage to the paintwork is not extensive, but

the electric tools are most suitable where severe

rusting of the metal has occurred.

602Repair of Vehicle Bodies