In order to achieve optically perfect painting results it is vital to understand the physical principles of the origin of color impression.
Color itself is a sensory perception.
The colors as we see them are the result of a combination of reflected colors from the spectrum. Physically speaking, these are electromagnetic waves with different wavelengths (and frequencies). The healthy human eye can recognize wavelengths between 0.36 µm (violet) and 0.78 µm (red).
If all the perceptible wavelengths of the spectrum impinge on the human eye at the same time, the impression of white light is produced.
Additive and subtractive color mixing
The Oswald color circle is based on subtractive color mixing, and enables the behavior of paints when they are mixed together to be represented.
Colors lying opposite each other are complementary colors and should not be mixed together as this will produce a dull (i.e. grey) shade. If green is added to red, the red becomes greyer, not greener.
Color shades which are side by side are partner colors and produce a mixed color shade. For instance, mixing red and blue produces a pure violet.
In addition, black and/or white may be necessary to produce a particular color shade.
- White makes the color shade lighter.
- Black makes the color shade darker.
- With black and white the color shade becomes more dreary or greyer.
Metamerism
Metamerism is the name of the effect which occurs when two colors appear identical in a particular light (e.g. artificial light), but the colors appear different under another light source (e.g. daylight).
The cause is the fact that the human brain, aided by the eyes, does not evaluate the wavelength, instead it evaluates the spectral intensity of the reflected light.
It is for this reason that color matching in practice must only ever be performed in daylight, or under special artificial light which is based on daylight.
Metallic and pearl pigments
Colored paints achieve their color effect by the addition of pigments. Pigments are colored, solid, very fine organic and inorganic particles which are insoluble in the binding material.
Metallic pigments
Aluminum platelets are added as pigment to form metallic paint.
The basis of pearl pigments is formed by mica, which is metallized with a silver or gold layer.
Depending on the angles of light and observation, the mica platelets reflect different proportions of light. Because of this, the color of the paint appears to the observer to change.
Pearl pigments produce a colored and light-dark reflected light effect.
Color codes and their determination on Ford vehicles
It is necessary to determine the correct color shade of the original paintwork in order to perform a professional and perfect paint repair.
Type plate
Type plate - location on Ford vehicles:
- Right-hand B-pillar - door rebate
- Left-hand B-pillar - door rebate
- Hood lock panel
- Left-hand vertical edge of inner front wing
- Right-hand vertical edge of inner front wing
- Right-hand engine compartment side member
- Left-hand bulkhead
- Right-hand bulkhead
- Luggage compartment interior
- Inner rear panel - luggage compartment
Because of the many parameters used, in a tabular system the color shade can also be determined by the lack of a parameter.
When using the color cards, emphasis is placed on matching of the original color shade with the color shade samples. For this reason this method is very helpful when the other parameters are not available.
Comparison of the results of both methods increases the certainty of using the correct original color shade and its formulation.
Additional certainty can be achieved during color shade determination by making a color sample plate. Here it is however important to apply the complete paint structure with base paint and clear lacquer onto a sample plate (1) in order to carry out a color shade and color coverage test.
The color shade comparison is done by comparing the vehicle paintwork with the sample plate (1). The color coverage test is possible by using the black test stripe (2): If the test stripe (2) is still visible after test painting of the sample plate (1), the coverage is not good enough.
By using this determination of the original color shade, the formulation and information on any very slight fine adjustments which may be necessary can be established.
Bare bodyshell plate
The color name is stamped on in the last row.