General Panels And Framework: Painting

General information- 

Painting the body has two basic objectives: protecting the surfaces of the panels from the elements and an aesthetic function of providing color and gloss.

The large number of chemical products used in painting operations require that special care must be taken over their handling and usage.

These painting operations involve the emission of paint fumes and solvent vapors which, if inhaled by the technician, could seriously affect the health and should only be performed in specialty spray booths.

The technician should always wear a mask and protective clothing.

Supplied air respirators must be used for total protection.

Equipment- 

The following equipment is used during painting operations:

• Supplied air respirator and protective clothing
• Masking and taping machines
• Spray booths and baking ovens
• Spray guns
• Infrared lamps
• Polishing machines

Protective clothing- 

When carrying out painting operations, suitable protective clothing must be worn to protect the technician from contact with harmful substances.

It is also advisable to use a barrier cream on any exposed areas (face, hands, arms), which must be removed at the end of the painting operations.

Courtesy of CHRYSLER GROUP, LLC

Supplied air respirator- 

This type of mask guarantees protection of the face and hair and is supplied with fresh air from the compressed air system used for the spray gun.

The air is purified further with a degree of separation close to 100%, by an activated charcoal filter fitted to the operator's belt.

The slight excess pressure created inside the helmet prevents the penetration of paint vapors.

The use of this mask is advisable for painting operations.

Spray booth- 

Spray booths are used for painting operations and for baking prepared parts. If the extent of the damage repaired is medium or large, it would be helpful to have a special spray booth and a hot air circulation oven for drying the paint.

The area should be equipped with an air conditioning system and filtered by purifiers, mainly comprising activated charcoal filters.

The optimum painting conditions that should be maintained in the booth during the painting stage are as follows:

• Constant temperature between 22 - 25 °C (71 - 77 °F)
• Constant relative humidity of 75 - 80%

The area in question could be:

• A combined painting and drying booth
• A separate painting booth and drying oven

Courtesy of CHRYSLER GROUP, LLC

Spray guns- 

Developments in the study of ergonomics and spray painting techniques have led to a type of High air Volume and Low atomization Pressure (HVLP) spray gun that allows a considerable reduction in paint overspray. The possibility of painting from the top or the bottom, in addition to preventing the formation of areas that are too wet or too dry, also allows access to areas of the bodywork that are difficult to reach. Special care has been taken over the ease of adjustment. This requires minimal, simple movements. This spray gun is extremely efficient, combining a very fine atomization capacity for any product, even water soluble, used by technicians at a pressure of 0.7 g (10 psi) or below. Thanks to these capabilities for using paint materials, it has been possible to achieve a considerable economic saving and improved working conditions.

Portable infrared (IR) lamps- 

If the operation is restricted to small touch-up, then the use of an oven is not practical. In these cases the paint can be dried using special infrared lamps fitted on parabolic mirrors. The use of one or more lamps positioned so that the surface that has been retouched is subject to an even temperature allows the paint film to bake and the result is comparable to that achieved in an oven.

This type of lamp greatly reduces drying times, thereby also reducing energy consumption. The lamp should only be used when the paint has already dried to the extent that dust is kept to the outside of the applied finish (flashed off).

Courtesy of CHRYSLER GROUP, LLC

Polishing machines- 

The paint should only be polished after the paint has been baked and after it has cooled down to ambient temperature.

Polish as necessary if there are defects in the paint work such as dust, overspray, sagging, orange peel or small scratches.

To remedy these defects, there are numerous products to be applied either manually or mechanically using a polishing machine.

The tool should be flat to the surface to be polished and should not be at an angle, in order to prevent the paint from overheating and producing circular concentric grooves.

Painting cycles- 

It should be pointed out that all painting operations must be carried out using appropriate equipment.

It is recommended to use the specific environmentally-friendly solvents for cleaning the equipment.

There is a body paint color identification plate on the vehicle, normally inside the hood, door or the luggage compartment lid/tailgate, which contains the original color identification code for repainting or touching up.

The products used must comply to the laws in enacted in terms of safety, hygiene and the environment. In the absence of these, use FCA approved paint systems. It is the responsibility of the final user to check beforehand that the conditions of usage are compatible with the recommendations in the supplier safety documents.

As far as the practical aspects are concerned, suppliers must certify that the aesthetic/functional features (e.g. mechanical properties, resistance to ageing and protection against corrosion) meet the corporate technical specifications when applied in accordance with the methods indicated in detail in the "product technical chart". Conformity with corporate specifications guarantees that the manufactured article will be in line with the original painting process quality standards.

This certification implies absolute adherence to the instructions laid down for the individual products on Safety Data Sheet that the supplier is obliged to deliver to the user in compliance with the legislation enacted in that country.

BODYWORK REPAIRS (PANEL SUPPORT) 

If a body panel is being replaced, check that dimensions, materials and surface treatment such as galvanizing and cataphoresis (also known as electrophoresis or e-coating) of the replacement part conform to the manufacturer's specifications.

Painting a panel secured to the bodywork by a mechanical fastening- 

• Clean the replacement panel with a low Volatile Organic Compound (VOC) wax and grease remover to remove any dust or grease that may be present.
• Gently dry sand the entire surface to be painted, using P320 grade sandpaper and a rotary/orbital power sander equipped with an dust extractor.

• Remove any residues of dust using compressed air and clean the entire surface using a low VOC wax and grease remover or an anti-static product.
• If during the above described operations (point 2) the sheet metal is accidentally stripped by the removal of the cataphoresis (electrophorisis/e-coat) and zinc coating, anti-corrosion protection must be restored by spraying a coat of epoxy primer on the affected areas.
• If appropriate, seal the joints by applying (single or two component) sealant that hardens at ambient temperature.
• Apply a filler, prepared previously following the instructions on the product technical chart, by spraying 2 crossover coats, at intervals of a few minutes, until the thickness recommended on the product technical chart is reached (2 - 4 crossover coats). Allow to flash for 10 to 15 minutes at ambient temperature before starting the drying process.
• Dry the base coat in an oven at a temperature of 40° - 60° C (104° - 140° F) about 30 - 40 minutes.
• When it is dry (and the panel is cold), dry sand the surface using P400 grade sandpaper to remove any defects.
• Remove any residues of dust using compressed air and clean the entire surface using a low VOC wax and grease remover and then finish off with an anti-static cloth.
• Prepare the paint (single stage or two stage) and/or the clear coat for spraying following the instructions on the technical chart for the product and use it within the recommended time.
• Apply the paint in 2 crossover coats with a few seconds in between until the desired thickness and color matching is achieved.
• Leave the paint to flash at ambient temperature, following the instructions on the supplier's technical chart for the time and conditions.
• For aesthetic finishes with single stage paint, dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• For two stage paint aesthetic finishes, proceed with the application of the clear coat (opaque base coat) prepared previously in accordance with the instructions on the technical chart with 2 or 3 crossover coats with intervals of a few seconds in between.
• Dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• Polish the surface at least 24 hours after the last coat has baked (and the panel is cold).

Painting a replacement panel secured to the bodywork by welding - 

• Clean the replacement panel with a low VOC wax and grease remover to remove any dust or grease that may be present.
• Fasten the replacement body panel to the bodywork by welding, preserving the integrity of the surrounding surfaces/elements by masking them and - wherever possible - by disassembling them.
• Wait until the work surfaces have cooled down, then proceed with removing the spatter and oxides that have formed in the Proximately of the welding seam.
• Brushing and dry sanding with P80 - P120 grade sandpaper.
• If the welding is visible and it is therefore necessary to restore the aesthetic aspect and continuity of the profiles, fill the joint and once it has totally hardened level it out using dry P100 - P120 grit sandpaper on a pneumatic random orbital sander.
• If during these operations the sheet metal is accidentally stripped by the removal of the cataphoresis (electrophoresis/e-coat) and zinc coating, anti-corrosion protection must be restored by spraying a high build epoxy primer on the affected areas.
• Remove any residues of dust using compressed air and clean the entire surface using a low VOC wax and grease remover or an anti-static product.
• If appropriate, seal the joints by applying (single or two component) sealant that hardens at ambient temperature.
• Apply a filler primer, prepared previously following the instructions on the product technical chart, by spraying 2 crossover coats, at intervals of a few minutes, until the thickness recommended on the product technical chart is reached (2 - 4 crossover coats). Wait for 10 to 15 minutes at ambient temperature before starting the drying process.
• Dry the primer coat in an oven at a temperature of 40° - 60° C (104° - 140° F) for about 30 - 40 minutes.
• Inspect the surface that has been worked on and remove any defects by dry-sanding the surface using P400 grade sandpaper.
• Remove any residues of dust using compressed air and clean the entire surface using a low VOC wax and grease remover and then finish off with an anti-static cloth.
• Prepare the paint (single stage or two stage) and/or the clear coat for spraying following the instructions on the technical chart for the product and use it within the recommended time.
• Apply the paint in 2 crossover coats with a few seconds in between until the desired thickness and color matching is achieved.
• Leave the paint to dry at ambient temperature, following the instructions on the supplier's technical chart for the time and conditions.
• For aesthetic finishes with single stage paint, dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• For aesthetic finishes with a two stage paint, proceed to apply the clear coat prepared earlier following the instructions provided in the technical sheet with 2 or 3 cross-coats and with a flash time of a few seconds between coats.
• Dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• Polish the surface at least 24 hours after the last coat has baked (and the panel is cold).

Partial repainting (one or more parts) of the bodywork- 

• Protect the areas not involved in the painting operation by masking.
• Restore the aesthetic appearance (profile and surface appearance) of the damaged panel. Lastly, level the area worked on using filler which can be applied after cleaning the surface using special detergent if the damage caused has not exposed the panel or if the panel has been exposed, the corrosion protection should be restored through the local application of an epoxy primer.
• After the filler is completely set, dry sand using P180 - P220 grade sandpaper.
• Then smooth the area to be re-painted with P150 or P220 grit sandpaper, widening the perimeter of the area to be worked on with a slight surface unevenness tapering off towards the exterior, taking care to eliminate all traces of oxidation from the stripped sheet metal.
• Remove any residues of dust using compressed air and clean the entire surface using a low VOC wax and grease remover.
• If appropriate, seal the joints by applying (single or two component) sealant that hardens at ambient temperature.
• Apply a primer filler, prepared previously following the instructions on the product technical chart, by spraying 2 crossover coats, at intervals of a few minutes, until the thickness recommended on the product technical chart is reached (2 - 4 crossover coats). Wait for 10 to 15 minutes at ambient temperature before starting the drying process
• Dry in an oven at a temperature of 40° - 60° C (104° - 140° F) metal temperature for about 30 - 40 minutes.
• Check the surface that has been worked on and remove any defects by dry-sanding the surface using P 400 grade sand paper.
• Remove any residues of dust using compressed air and clean the entire surface firstly using a low VOC wax and grease remover and then finish off with an anti-static cloth.
• Prepare the paint (single stage or two stage) and/or the clear coat for spraying following the instructions on the technical chart for the product and use it within the recommended time.
• Apply the paint in 2 crossover coats with a few seconds in between until the desired thickness and color matching is achieved.
• Leave the paint to dry at ambient temperature, following the instructions on the supplier's technical chart for the time and conditions.
• For aesthetic finishes with single coat paint, dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• For aesthetic finishes with a two stage paint, proceed to apply the clear coat prepared earlier following the instructions provided in the technical sheet with 2 or 3 cross-coats and with a flash time of a few seconds between coats.
• Dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time)
• Polish the surface at least 24 hours after the last coat has baked (and the panel is cold).

PAINTING PLASTIC COMPONENTS PROCEDURE 

(Thermoplastic type Polypropylene (PP) example: fascias)

Painting a replacement bumper (fascia)-

In the case of replacement, check that the replacement part complies with the corporate technical specifications in terms of dimensions, materials and surface treatment (black base with solvent or water adhesion promoter 3 ± 0.5 gloss with adhesion promoter and aesthetic finish function).

• Blow thoroughly with compressed air (filtered and purified) and clean using anti-static cloths/special detergents.
• Mask the areas not being painted in the body tint (example: rubbing strips, lower section, etc.).
• Prepare the paint (single stage or two stage) and/or the clear coat for spraying following the instructions on the technical chart for the product and use it within the recommended time
• Apply the paint in 2 crossover coats with a few seconds in between until the desired thickness and color matching is achieved.
• Leave the paint to dry at ambient temperature, following the instructions on the supplier's technical chart for the time and conditions.
• For aesthetic finishes with single stage paint, dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• For aesthetic finishes with a two stage paint, proceed to apply the clear coat prepared earlier following the instructions provided in the technical sheet with 2 or 3 cross-coats and with a flash time of a few seconds between coats.
• Dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• Wait until the treated surface has cooled down, then remove the masking.

• Take care over the non painted (black) parts to prevent the unpainted parts on show turning white.
• Polish the surface using fine abrasive paste and/or polish.

Partial repainting of a bumper- 

• Blow compressed air through the affected area involved in the repair to allow the complete removal of the aesthetic finish that has been affected.
• Mask the areas not being painted in the body color.
• Apply the primer and filler adhesion promoter, prepared previously following the instructions on the product technical chart, by spraying 2 crossover coats, at intervals of a few minutes, until the thickness recommended on the product technical chart is reached (2 - 4 crossover coats). Wait 10-15 minutes at ambient temperature before proceeding with drying.
• If needed, restore the aesthetic appearance (profile and surface aspect) of the affected component. Lastly, use filler to level the area being worked on.
• After the filler has completely set, dry-sand using P320 - P400 grade sandpaper.
• Then smooth the area to be re-painted with P150 or P220 grit sandpaper, widening the perimeter of the area to be worked on with a slight surface unevenness tapering off towards the exterior.
• Remove any residues of dust using compressed air and clean the entire surface using a plastic cleaner or an anti-static product.
• Dry in the oven at a temperature of 40° - 60° C (104° - 140° F) for about 30 - 40 minutes.
• Inspect the surface previously worked on and remove any defects by dry sanding the surface using P 400 grade sandpaper.
• Remove any residues of dust using compressed air and clean the entire surface firstly using plastic cleaner and then finish off with an anti-static cloth.
• Prepare the paint (single stage or two sage) and/or the clear coat for spraying following the instructions on the technical chart for the product and use it within the recommended time.
• Apply the paint in 2 crossover coats with a few seconds in between until the desired thickness and color matching is achieved.
• Allow the paint to dry at ambient temperature, following the instructions on the supplier's technical chart for the time and conditions.
• For aesthetic finishes with single coat paint, dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• For aesthetic finishes with a two stage paint, proceed to apply the clear coat prepared earlier following the instructions provided in the technical sheet with 2 or 3 cross-coats and with a flash time of a few seconds between coats.
• Proceed with drying in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• Polish the surface using fine abrasive paste and/or polish.

PAINTING A THERMOSETTING PLASTIC COMPONENT (Sheet Molded Compound (SMC), Bulk Molded Compound (BMC) Kneaded Molded Compound (KMC) types) - 

If a thermosetting element is being replaced, check that dimensions, materials and surface treatment (insulating primer) of the replacement part conform to the company's technical specifications.

Replacement- 

Visually check the integrity and suitability for use of the replacement part.

Repair- 

• Restore the appearance (profile and surface appearance) of the affected area.
• Blow compressed air on the affected repair area.
• Level the surface using filler; it can be applied after cleaning the surface using appropriate detergent.
• After the filler is completely set, dry sand using P320 - P400 grade sandpaper.

Painting- 

• Mask the areas not being painted, as appropriate; then overhaul the surface involved using P150 or P220 grade abrasive paper extending the perimeter of the area being worked on, in the case of a repair operation, through surface shading towards the outside.
• Remove any residues of dust using compressed air and clean the entire surface using a low VOC plastic cleaner or an anti-static product.
• Apply the primer coat, prepared previously following the instructions on the product technical chart, by spraying 2 crossover coats, at intervals of a few minutes, until the thickness recommended on the product technical chart is reached (2 - 4 crossover coats). Wait 10-15 minutes at ambient temperature before proceeding with drying.
• Dry in the oven at a temperature of 40° - 60° C (104° - 140° F) for about 30 - 40 minutes.
• Inspect the surface that has been worked on and remove any defects by dry-sanding the surface using P400 grade sandpaper.
• Remove any residues of dust using compressed air and clean the entire surface first using a plastic cleaner and then finish off with an anti-static cloth.
• Prepare the paint (single stage or two stage) and/or the clear coat for spraying following the instructions on the technical chart for the product and use it within the recommended time.
• Allow the paint to dry at ambient temperature, following the instructions on the supplier's technical chart for the time and conditions.
• For aesthetic finishes with single stage paint, dry in the oven at a temperature of 60° C for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• For aesthetic finishes with a two stage paint, proceed to apply the clear coat prepared earlier following the instructions provided in the technical sheet with 2 or 3 cross-coats and with a flash time of a few seconds between coats.
• Dry in the oven at a temperature of 60° C (140° F) for 40 minutes. Alternatively, dry using an IR ray lamp, following the instructions described by the manufacturer (distance of radiant panel from the surface to be dried; exposure time).
• Polish the surface using fine abrasive paste and/or polish.

PAINTING A THERMOPLASTIC COMPONENT- 

For the repair/painting, identify the specific product line for the materials constituting the surfaces on which the operation is to be carried out. Then proceed by following the instructions given on the technical charts, and the operating methods described in the previous paragraphs.