Spot Repairs and Blending Theory
Blending Single Stage Or Basecoat Colors
Is the process of allowing some of the original finish to show through the refinish coating.This reduces the visible difference between the original and refinish areas tricking the eye into seeing only one color.
Most blending are basiclly the same but some will have their own unique circumstances. The blending technique will have to be adapted for each repair. Blending can help disguise slight differences in colors but foreget the severe color matches. We have all seen examples of this. It is importand to tint the color as close as possible before blending. Keep the blend area as small as possible but effective.
Additives and paint techniques is the secerit to successful blending with basecoat/clearcoat finishes. You must consider that clearcoats are not perfectly clear and will change the appearance of a color and will generally blend the basecoat and clear the entire panel.
You should clear the entire surface of horizontal panels. Ultraviolet rays are very destructive to finishes, and will break down clearcoat blend lines on these panels.
Some paint manufacturers will specify a blend coat or add a product to help melt in the edge. They may specify that two coats of clear be applied to all repaired panels.
When blending in the sail panel area, vehicle and paint manufacturers may have specific recommendations for performing the repair. The repair procedure involves:
Neither the adhesion promoter or clearcoat is blended into the roof or deck lid. Blending into the roof would require clearing the entire roof panel to avoid problems with ultra-violet break down of the clear edge.
Multi-stage finishes on some vehicles are typically a standard tri-coat, with two clearcoats. In some finishes, a second type of clear, such as fluorine, is applied. Fluorine clears are typically applied over a standard urethane clear.
Always follow the vehicle or paint manufacturers recommendations when repairing multi-stage finishes. When working with these finishes:
• follow the repair sequence exactly.
• failure to follow procedures may void the paint warranty supplied by the vehicle manufacturer.
• only use products listed in the repair sequence. Do not substitute products.
• and the vehicle has a tinted clearcoat, a spray-out panel should be made to test the match of the basecoat and to see the effect the tinted clearcoat has on the color.
|This graphic shows a spot repair sequence for a fluorine clearcoat system.
1. Compound or sand with 1200—1500 grit sandpaper for better adhesion.
2. Apply first coat of basecoat.
3. Apply second coat of basecoat.
4. Apply third coat of basecoat or until hiding is obtained.
5. Apply color blender if necessary. Dry at 140°F (60°C) for 20 minutes.
6. Apply 3—4 coats of fluorine clearcoat. The area between 5 and 6 is faded out or blended if required. Dry at 60—70°
F (20° C) for 10 minutes between coats. After applying final coat, force dry at 170° F (75° C) for 45 minutes.
7. Polish with fine compounds.
This is one spot repair sequence, and should not replace specific instructions from either vehicle or paint manufacturers.
Tri-coat and other multi-stage finishes will become more common in the future. Fluorine clearcoats will also be more widely used.
This is an area of technology which will constantly change, requiring the painter to stay up to date by reading trade publications, and vehicle and paint manufacturer’s literature.
When working with tri-coat and multi-stage finishes, you must match the basecoat prior to applying the intermediate and clearcoats. Some vehicle manufacturers leave an area of basecoat that is not coated with mica or clear for comparing the basecoat spray-out to the vehicle.
You must make a let-down (sample) panel to determine the number of mica intermediate coats that must be applied to obtain a color match.
You should keep the repair area as small and dust and dirt free as possible. Because there are more coatings to apply, these finishes will require more room than asecoat/clearcoat systems.
As with pears and metalics, you should use an agitator cup to keep the mica suspended, appling thin, light coats of mica intermediate coats. Avoid a halo effect by applying the first mica intermediate coat to the basecoat only.
The Zone Concept
The zone concept divides the horizontal surfaces of the vehicle into zones defined by character lines and moldings that require refinishing of an entire zone or zones with basecoat, mica intermediate coats, and clearcoats.
Spot repair recommendations for tri-coats are now available, and are not as labor and material intensive as zone repairs. However, the zone repair is still a workable repair option, and may be required on certain vehicles.
This is one refinish manufactures recommendations for a spot or partial repair on a tri-coat system.
The same refinish manufacturer makes the following recommendations for a multi-panel repair
Check the let-down panel for total number of mica intermediate coats needed to match the OEM finish to areas marked C. Extend each coat beyond the previous one, with only the last coat extending into adjacent panel. Allow adequate flash time between coats.
This is a mica intermediate coat blending procedure for specific refinish paint company. For this product line, it is recommended that the:
1. first mica intermediate coat be applied to the area covered by the basecoat.
2. second mica intermediate coat be applied well beyond the edge of the first coat.
3. third mica intermediate coat be extended just beyond the edge of the first coat but within the second coat.
4. fourth mica intermediate coat be applied to just beyond the edge of the second coat.
The paint company recommends this application method to avoid a halo affect which is sometimes a problem when refinishing tri-coat finishes.
Full Panel Repair
|This panel repair technique was developed through cooperation between the vehicle manufacturer and a refinish manufacturer.|
After the vehicle has been prepared for painting:
1. Apply basecoat to full hiding over the entire panel, allowing each coat to flash.
2. Use the let-down panel to determine the correct number of mica intermediate coats. Apply the first two coats allowing each coat to flash.
3. Apply additional coats of mica, extending each into the adjacent panels. Extend each coat beyond the edge of the previous coat. Arc the gun at the blend edges.
4. Apply two coats of clear, allowing proper flash time between coats.
5. Blend the clearcoat using the recommended solvent.
|Tri-coat spot repair recommendations are similar.|
After the vehicle has been prepared for painting:
1. Apply basecoat to full hiding over the primer only, allowing each coat to flash. Keep the area of basecoat as small as possible, do not try to blend.
2. Use the let-down panel to determine the correct number of mica intermediate coats. Extend each coat beyond the edges of the previous coat. Blend a final mist coat of mica using an arcing motion of the gun at the edges of the blend.
3. Apply two coats of clear to the repair area, allowing proper flash time between coats.
4. If clear must be blended, blend the clearcoat edge using the recommended solvent.