How Paints Are Made 



The chemist has changed the paint industry. You don't 

 mix your paints nowadays. You buy them ready mixed 



By Henry A. Gardner, 



Assistant Director, The Institute of Industrial Research, Washington, D. C. 



No, this is not a soup kitchen. It is a room in a varnish factory where the expensive fossil resins 

 are melted in copper kettles of one hiondred-gallons capacity preparatory to mixing and canning 



THE owner of an average house will 

 probably be surprised to learn that 

 every time he paints it about one 

 hundred and fifty pounds of metallic lead 

 and zinc are used. For that reason, the 

 film of paint that series to protect the 

 wood may be thought of as a metal shell. 



The average mix- 

 ed paint contains in ^_ ?^*^J'2f**l*2''*^-^^*'*=^«*^ 



^ . ( 13 an air-ticbt shell protecting the wood 



every gallon about 

 ten pounds of lead 

 and zinc that has 

 been transformed 

 into white powders *>y *** = 

 by chemical proc- 

 esses. These white 

 powders, which are 

 called pigments 

 (white lead and 

 white zinc), are 

 ground in linseed 

 oil to produce paints, 

 duced by corroding 



Showing 

 impreg- 

 nation of 

 the wood 



fume which is cooled in long flue pipes. 

 Other forms of white pigments, such as 

 finely ground china clay and talc rock, are 

 used in the paint industry. An almost end- 

 less variety of chemical colors are manu- 

 factured for paint. These colors are made 

 from metals such as lead, zinc, chromium, 

 iron, antimony, cop- 

 per, cobalt and cad- 

 mium, as well as 

 from certain coal 

 tar dyes. Nearly 

 five hundred differ- 

 ent base colors are 

 used by the large 

 paint makers. 



Cross- section of a block of wood showing 

 impregnation of the wood by the paint 



White lead is pro- 

 metallic lead with 

 vinegar and gases or by subliming lead ores 

 in special furnaces. VVhite zinc is produced 

 by heating zinc ores with coal. At a high 

 temperature the zinc forms a white smoky 



Paints are Mixed 

 Like Dough 



In making paints, 

 the white pigments 

 are mixed in proper quantities with linseed 

 oil in large mi.xers containing revolving 

 knife blades and stirrers, such as are used in 

 a bakery for mixing bread dough. The 

 paste formed is then run through mills con- 

 taining closely set revolving plates of 



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