BASECOAT/CLEARCOAT REPAIR PAINT INFORMATION

MODELS AFFECTED: 1985 FRONT WHEEL DRIVE DEVILLES AND FLEETWOODS

The paint repair systems contained in this bulletin are recommended as a guide when repairing basecoat/clearcoat exterior finishes on 1985 Front Wheel Drive Devilles and Fleetwoods. While the original factory finish is enamel in the basecoat/clearcoat repair system, field repairs may be done with either lacquer or enamel repair systems. Section A outlines both spot/partial and full panel repair procedures for nonflexible parts; Section B outlines full panel repair procedures for flexible parts.

A. Nonflexible Panel Repair Procedures

Basecoat - Lacquer or Enamel

1. Wash panel(s) to be repaired with a mild detergent and water solution to remove any water soluble contaminants. Next, clean with a wax and grease removing solvent to remove any tar, silicone or other road film contaminants not removed with the detergent wash.

2. Repair and featheredge damaged area(s) as required.

3. If panel is metal, treat surface with a metal conditioner and conversion coating following label directions and allow to dry. Apply primer-surfacer to repair area. Allow primer-surfacer to dry 20-30 minutes before sanding.

4. Using wet or dry #400 grit or finer sandpaper, sand entire area(s) to be refinished with basecoat color. Areas to be clearcoated only, should be wet sanded with #600 or finer sandpaper or hand compounded following manufacturers' recommendations.

5. Reclean panel(s) with final wash solvent and tack wipe.

6. Apply one or two coats of adhesion promoter within moldings and/or breaklines of the panel section(s) to be refinished. Where the repair area is not confined within moldings or breaklines, apply adhesion promoter a minimum of 4-6" beyond antici- pated clearcoat application area. Adhesion promoter must extend beyond the area to be covered by the clearcoat unless the repair is confined by moldings or specific breaklines (Figure 1). Allow adhesion promoter to flash a minimum of 30 minutes before applying base coat color. Some enamel basecoats may not require the use of adhesion promoter for proper adhesion. Review paint manufacturers' recommendations for use of adhesion promoter with enamel systems.

7. Apply basecoat color. Refer to 7a for enamel basecoat application and 7b for lacquer basecoat application.

a. Enamel Basecoat Application

CAUTION:

There are a number of enamel paint systems available for service use, many of which require additives containing isocyanates. It is essential that all recommendations and warnings listed on the container label for materials selected be followed.

It is mandatory that adequate respiratory protection be worn. Examples of such protection are 3-M models #6984 and #6986 disposable respirators.

Such protection should be worn during the entire painting process. Persons with respiratory problems, or those allergic to isocyantes, must not be exposed to isocyanate vapors or spray mist.

1. Following paint manufacturer's directions, activate the enamel material. Mix enamel and activator thoroughly. The pot life of activated material is approximately eight (8) hours.

2. Reduce basecoat per label directions. Some activated enamel materials are ready to apply as packaged under normal conditions. Since conditions vary, check the viscosity of the activated mixture with a Zahn #2 Paint Viscosity Cup or equivalent. FoRow the paint manufacturer's recommendation for paint viscosity cup reading. To enhance flow out and leveling, up to 10% more enamel reducer than specified may be added to the activated mixture. The viscosity of the reduced color base color is important in order to match the original finish.

3. Using manufacturer's suggested air pressure, apply two medium-wet coats of enamel to achieve full color hiding. Allow first coat to set-up for 15-20 minutes before applying the second (final) coat. Unless manufacturer recommends otherwise, allow to cure overnight.

b. Lacquer Basecoat Application

1. Reduce base color 150-200% with an extra-slow drying lacquer thinner. The viscosity of the reduced base color is important in order to match the original finish. The best way to check viscosity of reduced paint is with a Zahn #2 Paint Viscosity Cup or equivalent. A cold can of paint will be thicker or more viscous than a can of paint stored at 65-70 degrees. Cold paint should be allowed to warm to room temperature (65-70 degrees), prior to reducing with thinner to manufacturer's recommended paint viscosity.

2. Apply base color using 35-45 lbs. pressure or as specified by paint manufacturer. Apply only the number of coats required to achieve full hiding. This will require two or three medium-wet coats. Allow each coat to flash approximately five minutes and spray each successive coat slightly wider than the previously applied coat. A premixed mist coat of clear acrylic paint may be used to melt overspray into base color. Allow to dry for 20 minutes before applying clearcoat. Do not sand basecoat color.

8. If basecoat color must be sanded, proceed as follows:

a. Allow base color to dry.

b. Sand base color with ultra-fine wet-or-dry sandpaper to remove imperfections.

c. Reclean and tack wipe the repair area(s).

d. Apply an additional coat of base color.

e. Allow to dry thoroughly before applying the clearcoat.

9. Apply clearcoat. Enamel clearcoat may be used over either enamel or lacquer basecoat colors. Lacquer clearcoat may be used only over lacquer basecoat color. Refer to Section 9a for enamel clearcoat application. Refer to Section 9b for lacquer clearcoat application.

a. Enamel Clearcoat

Because of better durability, polyurethane enamel clearcoat is preferred to lacquer clearcoat if shop conditions allow.

CAUTION:

There are a number of paint systems available for service use: however, many require additives containing isocyanates. It is essential that all recommendations and warnings listed on the container label for materials selected be followed.

It is mandatory that adequate respiratory protection be worn. Examples of such protection area: 3-M models #6984 and #6986 disposable respirators.

Such protection should be worn during the entire painting process. Persons with respiratory problems, or those allergic to isocyantes must not be exposed to isocyanate vapors or spray mist.

1. Following paint manufacturer's directions, activate the Polyurethane Enamel Clearcoat material. Mix material thoroughly. Pot life of activated mixture is approximately eight (8) hours.

2. Reduce clearcoat per manufacturer's direction. Some activated enamel materials are ready to apply as packaged under normal conditions. Since conditions vary, check the viscosity of the activated mixture with a Zahn #2 Paint Viscosity Cup or equivalent. Follow the paint manufacturer's recommendation for paint viscosity cup reading. To enhance flow out and leveling, up to 10% more enamel reducer than specified may be added to the activated mixture.

3. Using 50 lbs. pressure, spray two medium-wet coats of enamel clearcoat. Allow first coat to set-up for 15-20 minutes before applying the second final coat. Clearcoat should be applied over the entire panel whenever possible. When no breaklines are present, make all blends within the area previously covered with adhesion promoter (Figure 1).

b. Lacquer Clearcoat

1. Reduce clearcoat 125-150% with an extra-slow drying lacquer thinner to the viscosity recommended by the manufacturer whose paint you are using.

2. Spray two medium-wet coats of clear acrylic lacquer using 35-45 lbs. pressure. Allow the first coat to flash completely before applying the second coat. At least two coats must be used. Additional coats may be applied if desired. If additional leveling is desired, a final coat of premixed mist-coat material (clear acrylic and thinner) may be sprayed at 20 lbs. pressure. When no breaklines are present, blend all repairs within the area previously coated with adhesion promoter (Figure 1). Allow repair to dry overnight. Rub out using a with a fine hand or machine polishing compound.

B. Flexible Panel Repair System

FULL PANEL REPAIRS MUST BE PERFORMED ON FLEXIBLE PARTS. Spot repairs are not recommended because dry spray at the blend area of elastomeric color does not "wetout" satisfactorily.

CAUTION:

There are a number of flexible paint systems available for service use: however, many required additives containing isocyanates. It is essential that all recommendations and warnings listed on the container label for materials selected be followed. It is mandatory that adequate respiratory protection be worn. Examples of such protection area: 3-M models #6984 and #6986 disposable respirators. Such protection should be worn during the entire paint process. Persons with respiratory problems, or those allergic to isocyanates must not be exposed to isocyanate vapors or spray mist.

Flexible Undercoat Requirements

If the part to be painted is a GM service replacement part, it will be factory primed with an elastomeric enamel primer. If the original primer is not scratched exposing the base material, the repair procedure is to solvent clean the part, sand part with #400 grit paper or a red "Scotch Brite" pad, reclean part and apply elastomeric color.

However, if the base material is exposed or the part has been repaired using flexible filler material, a flexible primer surfacer must be used to provide the filling properties required to prevent a "bull's-eye" or highlighting of the bare base material or filler repair material after color is applied.

Flexible Primer Application

1. Clean entire part using a wax, grease and silicone removing solvent applied with a water dampened cloth. Wipe dry.

2. Featheredge the scuff or filler repair with #320 sandpaper, blow off dust and tack wipe.

3. Mix and apply four medium dry coats of flexible primer surfacer. Follow manufacturer's instructions for specific mix ratios and additives.

NOTE: Use a fast evaporating thinner as recommended to reduce the primer-surfacer and do not apply excessively wet coats. Bare flexible material surface and/or flexible filler materials have a tendency to swell from thinner absorption, resulting in a visible or "highlighted" repair.

4. Allow to dry at least one hour and block sand with #400 sandpaper. Sand the entire part with #400 sandpaper or red "Scotch-Brite" pad to remove all gloss in preparation for color application.

When paints are modified with a flex additive, the possibility of mixture "pot life" exists. Therefore, equipment should be cleaned using lacquer thinner immediately after use.

Body Color With Flexible Additive Systems

There are several flexible topcoat systems available for the painter's selections; in most cases, it is a matter of personal preference. Basecoat/Clearcoat material can be either enamel or lacquer-based.

Some manufacturers do not recommend the use of flex additives in their base color material, but do recommend its use for their lacquer clearcoat. Be sure to follow the same manufacturer's repair system for both base color coat and clearcoat applications.

Color Coat Application

1. Thoroughly sand the entire part with #400 sandpaper or red "Scotch-Brite" pad to remove all gloss. Reclean the part.

2. Mix the base color, flexible additive, if recommended, and thinner. Follow manufacturer's instructions.

3. Apply a sufficient number of coats to achieve complete hiding and color match. Allow flash time between coats.

4. Allow the base color coat to dry 30-60 minutes before applying the clearcoat. Do not sand the basecoat before applying the clearcoat.

NOTE: If sanding of the basecoat is necessary to remove imperfections, such as dirt or sags, sand with #400 grit or finer sandpaper, reclean the area(s). Apply one additional coat of base material and let dry.

Clearcoat Application

1. Mix and reduce clearcoat (lacquer or enamel) material as per instructions.

NOTE: Use flex additive if recommended by paint source.

2. Strain the mixture and apply 2-3 coats with 35-40 lbs. air pressure at the gun.

3. Allow each coat to flash completely before applying the next coat. Allow at least four hours air dry time or force dry for 30 minutes with a heat lamp at 180 degrees Fahrenheit before putting into service.

NOTE: Compounding is not recommended when a flexible additive is used in the top coat paint material. The mixture will dry with acceptable gloss. Compounding dulls the gloss of elastomeric finishes causing a flat appearance. The finish cannot be brought back to the same gloss level without applying more paint.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.