You picked up the car from the paint shop: the part is painted, there is a gloss, the car paint is selected according to the color code using online selection by VIN code on the website kraska-kiev.com.ua. But it’s worth placing a bumper or fender next to an adjacent part and the difference is obvious. This is called "color mismatch" or tone difference.
Why does color (shade) not match
The explanation lies in the nature of the paint itself and how the body ages.
Factors on the side of factory paint
Factory paintwork is applied by robots in several layers: primer, base enamel and two-component acrylic varnish (clear coat). Metallics and pearls contain aluminum flakes or mica pigments of a certain orientation. The robotic line provides the spray angle and curing temperature in the oven (~140–180 °C), which are basically impossible to reproduce in the workshop.
Aging paintwork is the main enemy
After several years of use, the factory enamel wears off:
- photochemical fading (UV degradation of pigment);
- thermal cycling (expansion/contraction of the varnish film);
- mechanical polishing with traces of washing.
As a result, the body and the new element represent two different objects from the point of view of the spectral reflection curve - even if the same RAL code or OEM code is indicated on the can.
Why decoding the VIN is only a starting point
VIN-matching (VIN decoding) on the website kraska-kiev.com.ua gives you the factory recipe at the time the car leaves the assembly line. The database (Standox, Glasurit, Sikkens, SpiesHecker) stores hundreds of variations of the same code, so-called “batch alternatives”, because even between production years the same code can have a different shade of aluminum flake.
But if the body is 5–7 years old, the VIN recipe only gives a starting position. Real color is what a spectrophotometer shows when applied to an intact part near the repair area.
Key reasons for the discrepancy: tableThe flip-flop effect and metamerism: two of the most insidious phenomena
Flip-flop is when pearl or metallic matches in color when viewed directly (angle ~45°), but diverges when viewed in sliding light (angle ~15°). This occurs due to different orientations of the flakes: in factory spraying they lie parallel to the surface, in manual spraying they lie chaotically. Control: change the air pressure and distance to the part.
Metamerism is a more subtle phenomenon. The two colors have the same brightness under a certain spectrum of light (say, in a box under a sodium lamp), but diverge in daylight D65. The reason is a different set of pigments with a visually identical result. There is only one solution: final control on the street in diffuse daylight, not in a box.
