TRI-COAT PAINT REPAIR PROCEDURES

SUBJECT: SERVICE PROCEDURES - TRI COAT PAINT REPAIR

VEHICLES AFFECTED: 1987-93 "V", 1988-93 " K" and 1989-93 "E" ------------------

THIS BULLETIN SUPERSEDES AND REPLACES CORPORATE BULLETIN REFERENCE NUMBER 811703**

THIS BULLETIN IS BEING REVISED TO INCLUDE 1990-1993 MODEL YEARS.

The Cadillac "V, K, and E" Cars are currently available in WHITE PEARL TRI-COAT COLORS which are unique from other colors. Unlike the current basecoat/clearcoat finishes, these colors are applied in a three-stage process, therefore, the repair will require additional attention.

Although these colors may appear to be identical, they are two different colors. The Allante uses code 55 White Metallic WA# 9069, where the Seville and Eldorado use code 93 White Diamond WA# 8933. These colors also use different base coat whites. The Seville and Eldorado use code 40 White WA# 8554, without the clear coat as the base coat white, while the Allante uses a base coat white unique to the WA# 9096.

NOTE: A Tri-Coat Paint Repair training program, course number 22010.08, is available through General Motors Product Service Training.

The Ultimate Basecoat/Clearcoat Color Shade (Figure 1):

Light that penetrates the surface of the cured paint film, reflects off the aluminum flakes, then passes around the pigment of varying densities which will produce the ultimate color shade.

The Ultimate Pearl Luster Effect (Figure 2):

Light striking the applied film of titanium dioxide on the flakes of mica creates the pearl luster effect by allowing the light to deflect at different angles. The light deflection determines the ultimate pearl luster effect you see.

The repair of these white pearl colors will require different techniques and a different application process. Many of the conventional application techniques used on non-clearcoat and basecoat/clearcoat metallic colors do not apply when repairing a tri-coat finish.

Non-clearcoat or basecoat/clearcoat metallic colors can be adjusted by the following variables:

1. Reduction (amount and choice of solvent) 2. Air pressure 3. Gun distance 4. Fluid adjustment 5. Fluid tip size

The color is affected as follows:

o Higher air pressure/increased reduction will cause a metallic color to shift to the light side on the face and dark on the flop.

o Lower air pressure/decreased reduction will cause a metallic color to shift to the dark side and go light on the flop.

Theoretically, when a metallic paint film is applied wet as it would be at lower air pressure and lower reduction, the aluminum flake will settle deeper in the paint film and be surrounded by the color pigment causing a darker appearance. The color will react in the opposite when the variables are reversed.

This theory does not apply to the white pearl tri-coat system. The white basecoat is a solid material, therefore, will not be sensitive to the same variables that affect metallic colors. On the other hand, the pearl coat (or mid-coat) is very sensitive to film build. With tri-coat pearl colors, film build is the primary means of a color match, NOT gun technique. For this reason a let-down panel should be used to determine the number of pearl coats required to match the OEM finish. This tool should be made prior to starting a repair. The let-down panel will be used to match paint on the repair vehicle and should be retained for future repairs.

NOTE: Separate let-down panels will have to be made for the STS Seville and the Allante because of the different colors involved.

"The Let-Down Panel":

The let-down panel should be used as an aid to determine the approximate number of pearl coats (mid-coats) that will be necessary to achieve a proper color match. This is done by comparing the various pearl coat film build areas on the let-down panel to a panel adjacent to the repair area prior to starting the repair. It can be made in the following manner, refer to Figure 1:

1. Apply the white base to hiding.

2. Mask the panel in five sections leaving the first section exposed.

3. Apply a single medium wet coat of the pearl material.

4. Remove the masking paper from the second section.

5. Apply a medium wet coat over the entire uncovered area of the panel.

6. Repeat the above steps until the five sections are completed, leaving only one coat on the last section.

NOTE: The let-down panel should illustrate five different film builds of pearl coat.

7. Once the panel is dry, mask off one half of the panel dividing it lengthwise. Apply two coats of clear on the unmasked half of the panel. Remove the masking paper and let the panel dry.

PAINT REPAIR TECHNIQUE OPTIONS

The successful repair of tri-coat finishes will depend upon the painter's repair technique and his/her experience with these colors. Remember: all tri-coat colors are designed to be repairable.

When Selecting and Using Materials:

o Use only top quality materials o Follow manufacturer's labeled instructions o Do not mix different brands of materials

The Success of a Paint Repair Depends Upon:

o An acceptable color match o A good blend with the original color o Proper build up of the pearl luster coat o A similar gloss and smoothness of the finish

REMEMBER: The pearl luster coat is very sensitive to film build. As the film build of the pearl luster coat increases, the color becomes darker. If the pearl luster becomes too dark to blend into adjacent areas, reapplication of the white base coat followed by pearl luster coats will be required.

Paint repair techniques for tri-coat finishes will consist of the following options:

1. Spot/Partial Repair

2. Full Panel Repair (picture frame, without blending)

3. Full Panel Repair (with blending of the pearl luster coat)

4. Allante Side Zone Repair

CAUTION:

If products containing isocyanates are used, it is MANDATORY that adequate respiratory protection be worn. Examples of such protection are: air line respirators with full hood or half mask. If not available, use a vapor/particulate type respirator the respirator manufacturer recommends as effective for isocyanate vapor and mist (unless local regulations prevail). Such protection should be worn during the entire painting process. Persons with respiratory problems or those allergic to isocyanates must not be exposed to isocyanate vapors or spray mists.

SPOT/PARTIAL REPAIR METHOD -------------------------- Use standard repair procedures for any metal damage. Sand, prime, and compound the same as for any paint operation.

1. Apply primer-surfacer as required. Follow labeled directions.

NOTE: For best results, a light color primer or sealer should be used under the base coat.

2. Wet sand the primed areas and areas where the base color will be applied with #400 grit sandpaper.

3. Compound or wet sand the areas to be painted with the pearl luster coat and clear coat with ultra-fine or finer sandpaper.

4. Apply adhesion promoter over the entire area to be painted.

5. Apply base color to hide. Blend as required.

6. Use the let-down panel to determine the number of pearl luster coats required to match the adjacent panels.

7. Apply the pearl luster coat over the white base area then blend beyond as required.

8. Apply clearcoat over the complete panel.

FULL PANEL REPAIR

(Picture frame without blending)

1. Apply primer-surfacer as required. Follow labeled instructions.

NOTE: For best results, light color primers or sealers should be used under the base white coat.

2. Wet sand the complete panel with #400 grit sandpaper.

3. Apply adhesion promoter over the complete panel.

4. Apply base color to hide.

5. Use the let-down panel to determine how many pearl luster coats will be required.

6. Apply pearl luster coats over the complete panel until color match is acquired. Allow sufficient flash time in between coats.

7. Apply clearcoats over the complete panel.

TYPICAL FULL PANEL REPAIR

(Blending into adjacent panels)

1. Apply primer-surfacer as required. Follow labeled directions.

NOTE: For best results, a light color primer or sealer should be used under the base coat.

2. Wet sand the complete panel with #400 grit sandpaper.

3. Compound or wet sand the complete panels that will be blended into using ultra-fine or finer sandpaper.

4. Apply adhesion promoter over the complete repair and blend panels.

5. Mask off the blend panels and apply the base coat to hide on the repair panel.

6. Use the let-down panel to determine the number of pearl luster coats required to match the adjacent panels.

7. Apply the required number of pearl luster coats to the repair panel allowing sufficient flash time in between coats and let dry. Pull back the masking paper form the adjacent panel to check for color match. IF THE REPAIR PANEL IS LIGHTER THAN THE ADJACENT PANELS, replace the masking paper and apply additional pearl luster to the panel.

8. Remove masking paper from the blend panels and apply one or more additional coats of pearl luster over the repair panel and onto the adjacent blend panels using an arching motion. If additional coats are necessary, extend each coat beyond the last on the blend panel.

9. Clearcoat the complete repair and adjacent blend panels.

TRI-COAT PAINT REPAIR SIDE ZONES

The styling characteristics of the Allante allows the side of this vehicle to be divided into three zones from top to bottom. These areas can be utilized for Spot/Partial, Full Panel Repairs or Blend Repairs using the following procedures.

1. Apply primer-surfacer as required. Follow labeled instructions.

NOTE: For best results, light color primers or sealers should be used under the base white coat.

2. Wet sand the complete panel with #400 grit sandpaper.

3. Compound or wet sand the complete panels that will be blended into using ultra-fine or finer sandpaper.

4. Apply adhesion promoter over the entire panel or panels to be painted.

5. Reverse tape mask the natural crease line along the entire length of the repair panel or panels to separate the repair zones.

6. Apply the base white to hide blending as required. Change the position of the reverse tape or masking to aid in feathering the base white.

7. Apply the pearl luster over the complete area of repair, blending as required. Change the position of the reverse tape or masking after one or two coats to aid in the feathering of the pearl luster material.

8. Remove the reverse tape and masking and apply the clear coat over the complete panel.

NOTE: The following procedure illustrates how the Side Zone Repair can be utilized on Allante deck lid or hood repairs.

1. Apply primer-surfacer as required. Follow labeled directions.

NOTE: For best results, a light color primer or sealer should be used under the base coat.

2. Wet sand the complete panel with #400 grit sandpaper.

3. Compound or wet sand the complete panels that will be blended into using ultra-fine or finer sandpaper.

4. Apply adhesion promoter over the complete repair and blend into using ultra-fine or finer sandpaper.

5. Mask off the blend panels and apply the base coat to the repair panel.

6. Use the let-down panel to determine the number of pearl luster coats required to match the adjacent panels.

7. Apply the required number of pearl luster coats to the repair panel allowing sufficient flash time in between coats and let dry. Pull back the masking paper from the adjacent panel to check for color match. IF THE REPAIR PANEL IS LIGHTER THAN THE ADJACENT PANELS, replace the masking paper and apply additional pearl luster to the panel.

8. Remove masking paper from the blend panels and reverse tape mash zone one of the quarter panel.

9. Apply one or more additional coats of pearl luster over the repair panel and onto zone one of the quarter panel. Change the position of the reverse tape or masking to aid in the feathering of the pearl luster coat.

10. Apply clear coat to the complete panels as necessary.

** BULLETIN REFERENCES: Corporate Ref.811703

General Motors of Canada 89-2-101 Cadillac Division T-88-168

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.