Flop (paint)

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Color flop of an interference paint on a VW Golf

The flop , more rarely flip-flop, describes the change in the coloristic properties of a material under different viewing angles. If the brightness changes , one speaks of a brightness flop ; if the color tone changes (additionally or exclusively) , one speaks of a color tone flop. The flop effect is used in paints , printing inks , cosmetics and plastics . Paints that produce these effects are called metallic paint (mainly brightness flop) or interference paint (mainly color flop) , depending on the type of effect .

description

The effect pigments used in the formulation are the cause of the occurrence of a flop effect .

Metallic effect pigments are usually platelet-shaped and align themselves in parallel in the paint. This means that a large proportion of the light is reflected on these, so that the brightness in the glancing angle is very high. Correspondingly, this portion of the light is missing at flatter viewing angles, so that the brightness is lower.

Interference pigments create their hue by amplifying and canceling out individual wavelengths ( interference ). Which wavelengths are amplified and which are extinguished depends on the viewing angle. This creates a color flop.

Measurement

In practice, the flop of a paint is determined either visually or using multi-angle spectrophotometers. Simple color measuring devices only measure the color shade at an angle and cannot be used for assessing effect paints. Multi-angle spectrophotometers determined the hue at several, usually five or six, angles. The flop is described by the colorimetric measurement values ​​of all measured angles.

The so-called flop index can be specified for the brightness flop. This is calculated from the brightness L * according to the CIELab system, measured at two different measuring angles.

Individual evidence

  1. ↑ a b U. Zorll: Römpp Lexikon der Lacke und Druckfarben. Thieme Verlag; Stuttgart 1998.
  2. ↑ G. Pfaff: Special effect pigments . 2nd Edition. Vincentz Network, Hannover 2007, ISBN 3-86630-895-7 .
  3. ↑ Calculation of the flop index on the homepage of X-Rite