Black and white

In 1991, vanilla beans were the highest valued spice import, with shipments totaling 69.0 million, followed by black and white pepper at 60.6 million, capsicum peppers and paprika at 42.6 million, sesame seed at 40.6 million, and cassia and cinnamon at 27.8 million. The most expensive spices, on a unit value basis, include saffron, 1116/kg average New York spot vanilla beans, 80.50/kg for Bourbon beans from Madagascar, Comoros, and Reunion, and 22.05/kg for Java beans and cardamom, 38.54/kg for grade AA bleached Indian and 3.88/kg for Guatemalan mixed greens. 

United States exports of spices in 1992 totaled 87.7 million up from 85.2 million in 1991 (Table 4). Dehydrated onion was the most important export spice product at 36.1 million followed by dehydrated gadic, 7.5 million capsicum peppers, 8.9 million black and white pepper, 5.8 million and prepared mustard products, 4.8 million. Canada, Japan, and Germany are the principal markets for United States spice exports. The production in the United States of temperate 2one spices is increa sing every year some of this output is exported as raw spice. 

Hydroquinone [123-31 -9] represents a class of commercially important black-and-white chemical reducing agents (see Hydroquinone,RESORCINOL, AND catechol). The following scheme for silver haUde development with hydroquinone shows the quantitative importance of hydrogen ion and haUde ion concentrations on the two half-ceU reactions that describe the silver—hydroquinone redox system ... 

Black-and-White Negatwe Vilm. Black-and-white photographs are usually reproduced from photographic prints. To preserve maximum details, eg, in fine-art reproductions, an original black-and-white negative may be scaimed direcdy. 

Thermal printing usually involves passing materials over a full-width array of electronically controlled heaters (a thermal printhead). This marks thousands of spots simultaneously, so pages print relatively quickly. Image data to control the printhead usually come from computer systems. Black-and-white and full-color systems are both practical. Color is slower and more cosdy to purchase and use, primarily because this involves three or four successive printing operations, one for each color used. 

J. Cogoh and co-workers. GraphicMrts Photographj Black and White, Graphic Arts Technical Foundation, Pittsburgh, Pa., 1981. 

Other Color Order Systems. The Natural Color System (24), abbreviated NCS, developed ia Sweden is an outgrowth of the Hesselgren Color Adas, and uses the opponent color approach. Here colors are described on the basis of their resemblances to the basic color pairs red-green and blue-yeUow, and the amounts of black and white present, all evaluated as percentages. Consider a color that has 10% whiteness, 50% blackness, 20% yellowness, and 20% redness note that the sum is 100%. The overall NCS designation of this color is 50, 40, Y50R iadicating ia sequence the blackness, the chromaticness (20 + 20), and the hue (50% on the way from yellow to red the sequence used is Y, R, G, B, Y). 

The initial uses of colorants in plastics were as extenders and additives. Carbon black and titanium dioxide were and are stiU used as fillers (qv) because of their low cost. Almost from plastics inception the limitation of black and white did not offer sufficient color choices for end users looking to differentiate their products. The increase in aesthetic requirements along with different performance requirements and resin compatibiUties led to a great expansion in the number of different chemical classes of colorants and forms in which these colorants are available in today s market. 

The first one-step print process was introduced by Land in 1947 (3). A comprehensive account of one-step photography detailing the development of instant black-and-white and color processes from 1944 through 1976 is available (4). Subsequent developments in instant photography and related reprographic processes through 1988 have also been described (5). A review of the chemistry of a number of instant color processes may be found in Reference 6. 

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