Chapter 17 Color Matching Objectives Describe color theory

Chapter 17 Color Matching

Objectives • Describe color theory and how it relates to refinishing • Define the terms relating to color • Describe the use of a computerized color matching system • Make let-down and spray-out test panels • Explain how to tint solid and metallic colors • Summarize the repair procedures for multistage finishes

Introduction • Color matching is the steps needed to make new paint look like existing paint • Even if you use body color code numbers and correct paint formula, the new paint may not be exactly the same color as the old • With today’s multistage paints and factory robotic painting, it can be difficult to match colors • This chapter will help you develop skills to match any type of paint

Color Theory • Color is caused by how objects reflect light at different frequencies into our eyes • When the eye sees a colored object, the object is absorbing all of the light except for the color that it appears to be • A black object absorbs almost all light, while polished chrome absorbs almost none • White light is a mixture of various colors of light • When light passes through a prism, it is broken down into its separate colors, the color spectrum

Lighting • Sunlight contains the entire visible spectrum of light and since vehicles will be seen in sunlight, it should be used to make color evaluations – Incandescent light has more yellows, oranges – Fluorescent has more violets and reds • Lumen ratings indicate brightness and lamps are normally between 1000 and 2000 lumens • Lamps may also be rated for a light temperature, measured in “Kelvin” – daylight is 6, 200 Kelvin – Choose lamps that are closest to sunlight

Color Blindness • Color blindness makes it difficult for a person’s eye to see colors accurately – Nearly 10% of all men have trouble seeing one or more colors • To do finish matching, the technician must be able to recognize colors as they actually are • It is important to see the overtones within a color, including shades of darkness or light

Dimensions of Color • To minimize confusion when painting, color should be based on value, hue, and chroma • The color tree is used to locate colors threedimensionally when matching colors • Value refers to the degree of lightness and the value scale runs vertically through the tree • Hue is also called color, cast, or tint, and moves around the outer edge of the tree • Chroma refers to the level of intensity and moves in spokes that radiate outward

Metamerism • Metamerism is how different light sources affect the appearance of paint pigments and metallics • A paint may have some red in it noticeable in daylight, but obvious under street lights • Color change results from new paint and OEM color formulas being made of different pigments – This causes pigments to look different under different light sources

Color Matching • OEM paint colors can vary slightly from area to area, especially with metallics • There can be a difference in the two finishes even if they are officially the same color • Whatever the reason for color variance, you must match the vehicle color itself • A color directory contains color chips, paint mixing formulas and other information – Locate vehicle paint code – Identify color chip next to it

Paint Formulas • Paint formula gives the amount of each ingredient needed to match an OEM color • Basecoat patch is a small area on the surface without clear to enable to check for color match – Sometimes located under the deck lid or hood • Suppliers may have newer paints ready-mixed • Older colors may have to be custom-mixed to order at the paint distributor • An intermix system is a full set of pigments and solvents mixed at collision repair shop

Computerized Color Matching Systems • Many spectrophotometer systems can input color data into a computer • The computer can use its stored data to determine how to mix or tint the color – Compares actual color to a set of color formulations – Recommends a tint in the formula – Keeps a record of the mixing or tinting procedure if vehicle returns

Color Variance Programs • If a particular OEM finish variation is noted often enough, the paint manufacturer may develop a color variation formula to match the OEM finish • Variance chips are several samples of slightly different colors to help match paints – Lay chips on vehicle under proper lighting – Use number code for closest matching chip to mix color

Spray Methods Affect Color • Refinishing technician control a number of variables to match new color to existing finish • Varying spraying technique can affect color • Technicians who spray wet end up with a darker color than those who spray drier, especially with metallics

Matching Solid Colors • For many years vehicles were solid colors, which reflect light in only one direction • Matching solid colors is easier than matching metallic or mica paints • A mismatch in a panel repair usually shows up more than a mismatch in a spot repair – Spot repairs are blended into surrounding areas • If there is a slight mismatch, blend coat and last colorcoat will allow show-through

Matching Metallic Finishes • Metallic color contains small flakes of aluminum suspended in liquid • Position of flakes and thickness of paint affect overall color • Dry application of paint makes color appear lighter and more silver • Metallic colors must be stirred and mixed thoroughly • To darken a metallic color, increase fluid flow, decrease fan width, air pressure, travel speed and use a slower evaporating solvent

Figure 17 -7. Metallic flakes in a color will reflect almost all light back out. The location and orientation of the flakes is critical to matching metallic finishes. If the metallic spray is too dry, the paint will look more silver because the flakes will not settle. If you spray too wet, the silver flakes will sink deeper into the color.

Matching Multistage Finishes • Multistage finishes consist of E-coat, colored primer coats, colored basecoats, mica intermediate coats or pearlcoats, clearcoats • Mica and carbon graphic pigments have special evaluation requirements • Mica may be coated with titanium dioxide • Thickness of titanium dioxide coating determines colors that are reflected

Zone Concept • Zone concept divides horizontal surfaces into zones defined by character lines and moldings • Requires refinishing entire zone with basecoat, mica intermediate coats, and clearcoats

Color Flop • Flop, or flip-flop, refers to the change in hue when viewing from head-on and from side • Flop occurs in paints containing metallic pigments – solid colors do not exhibit flop • Position of metallics in paint film can cause color of paint to change • Correct the problem by adjusting spraying technique to compensate for this effect • Addition of a small amount of white eliminates sharp contrast from light to dark

Figure 17 -9. Flop occurs when a metallic or multistage color looks different when viewed at different angles. Note how this metallic color appears different on this curved bumper.

Checking Color Match • Spray-out panel checks paint color and shows effects of technician’s technique on a test piece • Apply a primer that matches primer on vehicle, and apply a basecoat to full hiding • Apply a clearcoat to half panel, and allow to fully dry before evaluating • Uncleared section can be used to check color match with any noncleared patch on vehicle

Figure 17 -10. A spray-out panel tests the color match before applying the color to the vehicle. You must spray the test piece exactly as you are going to paint the vehicle body. By holding the test panel next to the vehicle color, you can see what the repair color will look like and whether the paint color must be changed.

Checking Color Match (continued) • To make a let-down panel, mask each layer to apply different amounts of basecoat and clearcoat • Duplicate your actual spray techniques • Compare different shades on let-down panel with existing paint on vehicle • Once made, let-down panel can be kept and used on vehicles with same color code • On the back of panel note color code, gun settings, and technician’s name

Figure 17 -11. A let-down panel tests a multistage paint system for match before spraying the vehicle. You must mask each layer to apply different amounts of basecoat and clearcoat. You can then use the panel as a large paint chip for comparison to the vehicle’s finish.

Blending Clearcoats • Clearcoats are not perfectly clear – they change the appearance of a color • Blend basecoat and apply clear to entire panel • You may have to step-out the clear if it must be blended • You should clear entire surface of horizontal panels • Blend into smallest area possible to help hide repair

Fluorine Clearcoat Repairs • Compound or sand with 1200 – 1500 grit paper • Apply 2 to 3 coats of basecoat until hiding is achieved • Apply color blender if necessary, and dry at 140 degrees F for 20 minutes • Apply 3 to 4 coats of fluorine clearcoat, dry at 6070 degrees F for 10 minutes between coats • After applying final coat, force dry at 170 degrees F for 45 minutes, polish with fine compounds

Tricoat Spot Repair • Halo effect is an unwanted shiny ring or halo that appears around a pearl or mica color repair • Caused by the paint being wetter in middle and drier near outer edges • Avoid a halo by applying first coat of mica to basecoat only • Allow a larger area in which to blend intermediate mica coats • Keep tricoat repair area as small as possible

Tricoat Panel Repair • Apply primer to area over the body filler, and apply adhesion promoter to a large area • Apply two or more coats of basecoat to areas to full hiding, extending each coat slightly beyond the previous one • Extend each mica intermediate coat beyond previous one, with only last coat extending into adjacent panel • Apply two coats of clear to entire repair area, ending at panel ends

Blending Mica Coats • Apply mica intermediate coat to area covered by basecoat • Apply a second mica intermediate coat well beyond edge of first coat • Apply a third mica intermediate coat so that it extends to between first and second coats • Apply a fourth mica intermediate coat to just beyond edge of second coat • Zone repair is an option that may be required on certain vehicles

Matching Mica Colors • Many base-clear finishes contain mica pigments, and some are especially challenging to match • Because finish may not provide full hiding, color of the primer may show through • If technician applies color to full hiding, there may be a color mismatch • Color effect test panel is required for base-clear finishes that contain mica

Why a Color Mismatch? • Tinting should be used only as a last resort • If color mismatch, check whether finish has faded • Check that vehicle’s paint code and stock number of color are correct • Check that pigment and metallic flakes were properly mixed, and that correct amount of reducer was added • Check that test panel dried, and that color comparison was made after applying clear

Tinting • Tinting is used to adjust color variations in shades to match color from manufacturer • Tinting is used to adjust color on an aged or weathered finish • Tinting makes a color for which there is no formula, or for which there are no paint codes • Before tinting, determine if a color variance chip or formula is available • Some paint manufacturers produce metallic tinting bases to correct a specific problem

Figure 17 -17. Tinting can be complex. Take your time and compare the tinted color to the color on the vehicle. One or more test panels may be needed on hard-to-match color, especially metallic and pearl colors.

Summary • Same shade of paint will look very different under incandescent and fluorescent lights • Very important to view a color in daylight or under a balanced artificial light • Color should be based on value, hue and chroma • Two ways to check color match are: – Spray-out panels: used with conventional paints – Let-down panels: used with multistage paints