68 



PAINT TECHNOLOGY AND TESTS 



materials, in some cases as high as 40%. Graphite is usually 

 mixed with other pigments, such as red lead and sublimed blue 

 lead, thus serving better as a paint coating. The difference 

 in physical appearance of the various carbon pigments is inter- 

 esting, as each pigment has characteristics of its own. In 

 graphite we find a great tendency toward agglomeration or 

 massing of particles. 



Mineral Black. Mineral black is a pigment made by grinding 

 a black form of slate. It contains a comparatively low per- 

 centage of carbon and consequently has low tinting value. It 

 finds use as an inert pigment in compounded paints, especially 

 for machine fillers. The pigment has a flocculent appearance, 

 the particles showing a strong tendency to mass. 



Photomicrographs of two combination paint pigments are 

 here given, to show the various pigments as they appear under 

 the microscope, when in combination. 



PERCENTAGES OF OIL REQUIRED FOR GRINDING VARIOUS 

 DRY PIGMENTS INTO AVERAGE PASTE FORM 



White lead (corroded) 



White lead (sublimed) 



Zinc lead (American) 



French process zinc oxide 



American process zinc oxide . . 



Blanc fixe 



Barytes (natural) 



Paris white (whiting) 



Terra alba (gypsum) . . .' 



Floated silica or Silex 



Kaolin (China clay) 



Asbestine 



Blue, ultramarine 



Blue, Chinese or Prussian .... 



Black, gas carbon 



Black, lamp 



Black, drop . 



Black, bone 



Brown, mineral 



Brown, Vandyke 



Chrome yellow, lemon ........ 



Chrome yellow, medium 



Chrome yellow, orange 



Chrome yellow, dark orange . . 



Chrome green, Chem. pure light 



Chrome green, Chem. pure ex- 

 tra dark 



Chrome green, 25%, color light 



Chrome green, 25%, color extra 

 dark 



9% 

 10% 



12% 

 17% 

 16% 

 30% 

 9% 

 20% 

 22% 

 26% 

 28% 

 32% 

 27% 

 50% 

 82% 

 72% 

 60% 

 50% 

 24% 

 50% 

 23% 

 30% 

 20% 

 15% 

 21% 



25% 

 13% 



17% 



Graphite (pure) ............. 



Indian red, (98%) .......... 



Ochre, yellow, American ...... 



Ochre, yellow, French ........ 



Ochre, golden .... ........... 



Red, Venetian .............. 



Red, Oxide ................ 



Red, Tuscan ............... 



Red, Turkey ................ 



Red, lead .................. 



Red, lake. . ................. 



Sienna, Italian, raw .......... 



Sienna, Italian, burnt ........ 



Sienna, American, burnt ...... 



Sienna, American, raw ....... 



Ultramarine green ........... 



Umber, Turkey, raw ......... 



Umber, Turkey, burnt ....... 



Umber, American, burnt ..... 



Umber, American, raw ........ 



Verona green (terra verte or 



green earth) ---- .... ____ 

 Vermilion, English (quicksilver) 

 Vermilion, American (chrome 



red) ................... 



Paris green, American ........ 



Zinc chromate (permanent yel- 



low) ................... 



40% 

 20% 



26% 



28% 

 28% 

 23% 

 25% 

 27% 

 28% 

 12% 

 55% 

 52% 

 45% 

 38% 

 40% 

 28% 

 48% 

 47% 

 36% 

 38% 



32% 

 14% 



16% 



23% 



15% 



