Cochise College           Student Papers in Geology

Geology Home Page                   physical geology  historical geology  planetary  gems           

Roger Weller, geology instructor

wellerr@cochise.edu

Paint Pigments
by Conor Mahoney
Physical Geology
Spring 2013
         

 

Pigments: Color Matters




















 

http://i.imgur.com/VXz3e4a.pnghttp://www.bradshawfoundation.com/lascaux/gallery/lascaux3b.jpgMerriam Webster defines a pigment as : a substance that imparts black or white or a color to other materials; especially : a powdered substance that is mixed with a liquid in which it is relatively insoluble and used especially to impart color to coating materials (as paints) or to inks, plastics, and rubber.  Some obvious pigments that probably go overlooked by anyone who isn’t in a 4th grade Earth and Environmental science course would be chlorophyll and melanin; these are the pigments that give plants and animals their respective skin colors. Pigments are used in nearly everything man has ever saw fit to color, from natural pigments such as those used to paint Lascaux Cave in France to lipgloss from Victoria Secret (Figure 1).  Iron oxide pigments are prominent among inorganic pigments and are the most common used in consumer based products.  This is not a new trend; in fact, pottery found from the eighteenth century BC underwent x-ray tests in a study performed by numerous chemists and, geologists to be composed of iron oxide pigments (Figure 2).
 

Mankind has gone a long way from blood and berry based pigments on the inside of cave walls.  Now pigments are made en masse using immense automated facilities with very little interaction from human operator; however some locations such as the Yakovlevsky Ore Mine in southeastern Russia are natural deposits for and implementations to produce the pigment at the source have been proposed (Kuskov).  Iron Oxide pigments are the most used for coloring, the primary colors being yellow, black, and red (China Chemical Reporter).  Red pigments such as those found in the Yakovlevsky are especially sought after, as the color red is used in primarily in the production of bricks and other architectural coatings as well as cosmetics more than any other color.  Red pigments are obtained after superheating black slurry to eight hundred and fifty degrees Celsius in a kiln until the black pigments turn red.  China is another primary source for the four major producers of iron oxide pigments: Bayer, Lockwood, Elementis and LANXESS; the total output of these companies accounted for 120,000 tons or 15% of the entire output of the China’s iron oxide pigments in the year 2011 (China Chemical Reporter).








 





Great YouTube Video on Pigments
http://www.youtube.com/watch?v=zKFs2qX-Fkc

     The process of creating inorganic pigments begins with a recycled chemical salt such as iron (II) sulfate.  Warm water and recycled high quality scrap are added to the salt along with various chemicals.  Occasionally a technician will observe the hue of the slurry and deem modifications necessary if it is not the correct hue. The slurry is then transferred to a giant metal drum which rotates the slurry across its surface where it permeates through a filter cloth leaving a more concentrated solution on the outside of the drum called filter cake which has the consistency of wet sand.  The filter cake is then pressed into a large rotating disc and blasted with hot air until it is dried into pigment powders.  The process is identical for black pigments, however instead of recycled scrap, cast iron filings are used to establish a black base.  In order to create red pigments a portion of the black paste is filtered into a kiln to dry.  Within the kiln the paste is heated and mixed and blasted with hot air until it hits 850 degrees Celsius at which point the black paste will turn a bright striking red (Discovery Channel).









 

http://static.newworldencyclopedia.org/thumb/0/0f/Empire_State_Building_Dec.2005.jpg/300px-Empire_State_Building_Dec.2005.jpg
     The growing trend of urbanization throughout the world has caused companies such as LANXESS to increase production and LANXESS itself has plans to create a new red pigment plant at the Ningbo Chemical Park in China.  The plant will be roughly seven hectares (7000 square meters) in size and will have a proposed output of 25,000 metric tons initially; this pales in comparison to the plant LANXESS has in Shanghai which has an output of 38,000 metric tons; In January of 2013 China exported 12,767.782 metric tons of pigments with an export value of $95,816,000.  To put this in perspective, 12,767.782 metric tons is equal to 28,148,141,004.42884 pounds.  That is the equivalent of exporting almost thirty five Empire State buildings or seventy two clones of the largest blue whale ever weighed.  Also, note, that these numbers apply only to the month of January, 2013 (China Chemical Reporter).

 

Cosmetic companies are some of the primary users of iron oxide pigments.  Lipstick, lipgloss, mascara, blush, foundation and powder all use iron oxide pigments.  In order to make bricks, BayFerrox takes the aforementioned red pigments and applies a plunger to them to acquire the rectangular prism shape.  The whole purpose of pigments revolves around color, be it coloring of bricks to reflect some of the sun’s rays in order to lower temperatures within the home or the naturalized epidermal staining of skin grafts.  Conventional tattooing uses iron oxide pigments almost exclusively; however that definition of tattooing is not reserved for the standard image one associates with tattooing and instead also applies to medical post-surgical skin grafts.  Doctors Spinelli, Isenberg, O’Brien, and Shapiro performed a study involving the usage of iron oxide based pigments on surgical scars to achieve eventual uniform pigmentation in rats (Spinelli).  The process used in this experiment is similar to those used to provide uniform skin pigment to vitiligo sufferers.









 

http://a57.foxnews.com/global.fncstatic.com/static/managed/img/Scitech/660/371/marzed.jpg?ve=1

     Pigments are everywhere.  From makeup to tattoos to clothes to bricks; any product mankind as a species produces now will probably have some form of pigmentation applied to it.  Picking out nearly any cosmetic makeup product will reveal the words “iron oxides”.  As a consumerist culture dominated by ever larger urban centers which in turn are all covered in weathering resistant pigments to provide color and protection to the building facades.  While natural pigments can be found in ore mines such as that in the Yakovlevsky mine in Russia chemically produced pigments are much more popular among companies in spite of the natural pigment’s lower cost of production.  Mars, the red planet, gets its famous red coloring from the iron oxides found in its soil.  From medical applications to brick building to celestial bodies pigments are everywhere and are an unavoidable substance in everyday life.
 

References

Lin, Zhihua. "Review And Outlook For China's Iron Oxide Pigment Market." China Chemical Reporter 23.4 (2012): 19. Academic Search Complete. Web. 25 Apr. 2013.
 

Kuskov, V. B., and Ya. V. Kuskova. "Development Of Technology For Preparing Iron Oxide Pigments." Metallurgist 54.3/4 (2010): 192-194. Academic Search Complete. Web. 25 Apr. 2013.
 

F. Giannici, et al. "Decorated Pottery Study: Analysis Of Pigments By X-Ray Absorbance Spectroscopy Measurements." Journal Of Applied Physics 101.6 (2007): 064909-8. Academic Search Complete. Web. 25 Apr. 2013.
 

"LANXESS To Build New Pigment Plant In Ningbo." China Chemical Reporter 24.5 (2013): 12. Academic Search Complete. Web. 25 Apr. 2013.
 

F. Giannici, et al. "Decorated Pottery Study: Analysis Of Pigments By X-Ray Absorbance Spectroscopy Measurements." Journal Of Applied Physics 101.6 (2007): 064909-8. Academic Search Complete. Web. 25 Apr. 2013.
 

"Import And Export Data In China In January 2013." China Chemical Reporter 24.5 (2013): 21-25. Academic Search Complete. Web. 25 Apr. 2013.
 

Kuskov, V. B., and Ya. V. Kuskova. "Development Of Technology For Preparing Iron Oxide Pigments." Metallurgist 54.3/4 (2010): 192-194. Academic Search Complete. Web. 25 Apr. 2013.

"Production Of Inorganic Pigments In China." China Chemical Reporter 22.21 (2011): 16-17. Academic Search Complete. Web. 25 Apr. 2013.