Re: Re: Pigmentation
statman24 said:
Can you explain?? Just curious.
Without getting too technical, paint/coatings are comprised of vehicle (resin system), pigments, solvents and/or water, and additives. The vehicle (resins: eg. acrylic, polyurethane, alkyd, etc) give the coating it's basic properties. Pigments - which include color pigments (both organic and inorganic) and effect pigments (mica/pearlescent, aluminum etc) also influence properties and durability to some extent.
Exterior automowive coatings are applied at a dry film thickness of approximately 0.5 - 2.5 mils, depending on quality and whether it is a primer, basecoat, clearcoat, etc. Basically, the color basecoats that Toyota uses are applied at a film thickness of 0.8 - 1.2 mil (20 - 30 microns). The coating has to "hide" at that film thickness as well as contribute to other properties. White colors utilize a pigment called TiO2 (titanium dioxide). TiO2 (assuming the right grade is used) has excellent exterior durability (i.e. resistance to fading/color change). However, a high level of TiO2 must be used in the formulation to achieve hiding at the applied film thickness - much higher levels that with many other pigments). Such a high loading can and does effect properties such as flexibility and chip resistance to some degree. In many cases this necessitates modifications to the resin (vehicle) system that effect other properties.
This does not mean that white colors/basecoats are inferior in any way. Coating technology, like any other technology, necessitate some degree of trade-off.
Other colors/pigments have their own advantages and disadvantages that must be taken into account when formulating the coating. I will say that basic silver color basecoats are probably the most "forgiving" as far as overall properties and durability. This was not the case years ago but effect pigment technology has progressed quite a bit in recent years.
Personally, I find white vehicles very boring so they would be one of my last choices - but to each his own!