Henry Ford was once famously quoted to the effect that the American car buyer could have “any color he wants, as long as it’s black.”

Ever since that statement became inaccurate—sometime in the late 1920s—and auto manufacturers began applying a varied palette of hues to their products, color blending has been essential to repairing an automobile body.

Through the years since those nitrocellulose lacquer days, carmakers have created increasingly sophisticated finishes to brighten and distinguish their products from competitors. First came clearcoats, followed quickly by metallics, then pearls. In this ever-ascending scale of complexity, the pearls produced tri-coats, including colors that are virtually transparent. These developments, while enhancing a vehicle’s appeal to car buyers, created nightmarish problems when it comes to blend repairs—even for gifted and experienced painters.

To start with, a blend involves several elements: the hue, value and chroma of the color; texture or the amount of orange peel; gloss or distinctness of image, as well as metallic distribution. Blending a color creates the illusion that minimizes a color, texture metallic or flop mismatch. The painter, in effect, must make the repair invisible. The edge of the sprayed color must blend into the surrounding area rather than stopping at a hard break-line, such as a door gap or moulding.

Panel repair procedure

To do a proper panel repair, you must first decide which panels will be blended. Then, prepare those panels. Every paint manufacturer publishes tech manuals with directions for blending. Check with your paint supplier for this information, but here is a general procedure:

After cleaning, abrading and cleaning the surface again, mask all adjacent areas. Now you’re ready to apply the primer. All paint makers offer a colored primer system that assists in hiding basecoats. You can go with this or with a colored groundcoat over all the repaired areas before applying the basecoat. The groundcoat minimizes the amount of paint needed to attain full coverage.

Before applying the basecoat, check the color with a sprayout. For basecoat/clearcoat finishes, the sprayout must include a clearcoat. If the color is close enough to blend, start spraying. The closer the color is in the first place, the easier it is to blend. Pick an appropriate variant color for the vehicle.

Most paint manufacturers make basecoat blenders. These are usually unpigmented basecoat resins. After reducing and adding color blender to the basecoat, spray the mixture on the edge of the color blend area to help blend the repair with the OEM color.

Basecoat color application

Apply the first coat of basecoat color over the repair area and follow with an application over the complete affected panel, according to paint manufacturer’s specifications. Apply the second coat of color over the complete affected panel and extend the coat into adjacent panels for several inches. Allow the paint to flash, then feather off all application of color at the blend area edges.

Basecoat blending tips for success

Application equipment does have an impact on results. On tough blends, use a narrow fan, reduced fluid flow and reduced atomizing air pressure that is just high enough to give sufficient breakup. Gravity and HVLP equipment usually perform better than siphon guns.
For optimum results, use smaller fluid tips (1.5 mm or smaller) set to the lowest air pressure that still gives good atomization.
Agitate ready-to-spray paint thoroughly, especially high metallics and pearls, and be sure to spray immediately after loading the gun. Don’t allow paint to settle in the gun cup. Stir paint again between coats if necessary.
Be sure that all surfaces are properly prepared.
Before applying the clearcoat, allow the basecoat color to dry according to manufacturer’s recommendations. Remember, the more coats of basecoat applied, the longer the dry time. Give it long enough so that solvents flash off. Then, carefully tack off the refinish areas using a basecoat tack rag, being sure not to disturb the metallic effect in the paint. Basecoat tack rags aren’t as sticky as standard tack rags, and therefore there is less chance of disturbing the basecoat.

Clearcoat application

Some manufacturers recommend an adhesion promoter before applying the clearcoat. If so, be sure to sand the area with 1,200- to 1,500-grit, then apply the adhesion promoter.
Mix the clear with required components, following label directions carefully. Apply the first coat of clear to the repair panel, and extend the application beyond the blend area, where it is feathered off. Apply the second coat to the entire affected panel and to the entire front and rear adjacent panels. Apply a third coat of clear to all repair areas if polishing is required.
Avoid extending the clear into an area that was not properly scuffed. This can cause a peeling problem later.
After the clear dries, wet sand and polish the tapered edge as recommended by the paint maker.

Tricoat panel blend

With a tricoat (pearl) repair, be sure to paint adjacent panels with both basecoat and pearlcoat color and clearcoat the entire area.
Try to keep the repair and blend areas as small as possible. You may want to employ a two-gun approach, which can be used with both base color and pearlcoat blend edges. One gun contains regular reduced pearlcoat. Use the first gun to apply the pearl to the main repair area. Keep the pearlcoat within the repair area.
A second gun (keep it in reach) contains a mixture of pearl and color blender to make the second coat more transparent. Use this gun to extend blend edges.

Almost every repair will require some sort of blend procedure, so the ability to do a blend correctly and professionally is a major asset for every auto body repair shop. The results of a good blend are twofold: a satisfied customer and an easier job for you.

The blend panel controversy

No discussion of blending in today’s auto body repair industry would be complete without addressing the controversy around blending and what constitutes a blend panel.

Some shops have reported that insurers are requiring them to accept reduced refinish times on repaired panels (when basecoat is not being applied to the entire panel) because the insurer considers the repair a blend panel.

“A blend panel is an adjacent undamaged panel that is painted for color match purposes only,” says Dan Risley, executive director of the Society of Collision Repair Specialists.

“Changing the definition shouldn’t change how repairers are compensated for the work they perform.”

“Simply stated,” he continues, “if the fender is replaced on a vehicle, in most instances, the technician will blend into the door for color match purposes only. The [adjacent undamaged panel] door is a blend panel. If the fender only had a small amount of damage and the technician was able to refinish that panel such that he/she would not have to blend into the [adjacent undamaged panel] door, the fender would not be considered a blend panel. In fact, additional labor [as per the P-pages] would be required on this panel because the technician would need to featheredge, prime and block the damaged area. Repairers need to use the P-pages because oftentimes there is labor such as featheredge, prime and block that requires an on-the-spot evaluation before being added to the estimate as a line item.”

Risley, in an attempt to clarify the situation, wrote an article for the SCRS Web site that appeared in the July 2004 Straight Talk section of ABRN. For the article, he contacted the information suppliers ADP, Mitchell, Motor (supplier for CCC), and Trevethan Enterprises. Posing the question, “What is a blend panel?” he received these responses:

ADP: Blending is defined as the application of color to a portion of an undamaged adjacent panel for the sole purpose of facilitating the appearance of color match into the area.

Mitchell: A blend operation requires basecoat application to “less than full coverage” to blend new color with existing color for color match. (See note below for more on this).

MOTOR: Blending may be necessary for adjacent body components to avoid noticeable color variation between newly applied paint and the existing paint of adjacent components or areas.

Trevethan Enterprises: Blending or a partial basecoat application may be necessary to facilitate color match in adjacent panels. This includes the proper application of clearcoat to manufacturer specifications.

Risley says the response to his article has been “tremendous—very positive,” and he has received many requests for copies. “Shops are using it when they try to address the issue with insurers.”

Because the Mitchell response was somewhat truncated, we contacted Tom Fleming, Mitchell’s vice president of database development, who clarified the statement: “Major paint manufacturers have provided the following clarification: ‘Spot repair within the panel is differentiated from a blend operation. A spot repair requires undercoat application (i.e. sprayable etch primer, sealer, etc.) and base coat application to full coverage plus basecoat application to blend new color with existing color for color match. A blend operation requires basecoat application to ‘less than full coverage’ to blend new color with existing color for color match.”

Fleming notes that the statement is the consensus of the listed paint makers and not Mitchell’s definition of a blended panel. Mitchell’s Procedure Explanation 28 provides a labor time formula to blend a panel, along with this explanation: “Blend Adjacent Panel(s)—With some colors, it may be necessary to blend color into adjacent panels to obtain acceptable match.”