404 



Popular Science Monthly 



been grown in the northwestern States, in 

 Canada and in India for many years. A 

 new and important source of supply is 

 Argentina, in South America. The flax- 

 seed is crushed and then heated to a tem- 

 perature of about 160 degrees. It is 

 pressed in large hydraulic- presses and 

 yields from 

 26% to 34';o of 

 linseed oil. 

 This oil is set- 

 tled or filtered, 

 and then treat- 

 ed chemically 

 to remove cer- 

 tain mucilag- 

 inous matter, 

 called "foots," 

 before it is 

 ready for the 

 varnish maker. 



China Con- 

 tributes a Won- 

 derful Oil 



China wood- 

 oil is another 

 large factor in 

 varnish making, 

 is the product 

 the "Tung nut," a 

 nut growing in 

 China. The nut 

 has a soft shell and 

 a meat similar in 

 appearance to the 

 Brazil nut. The 

 shells are removed, 

 then the nuts are 

 crushed, heated and 

 pressed in the most 

 primitive way to 

 produce the oil 

 which is shipped to 

 this country for 

 varnish making. 

 The oil has peculiar 

 waterproof qualities not common to lin- 

 seed oil. 



Turpentine is the product of the long- 

 leaf pine tree, grown in the Southern 

 States of this country. The sap of this 

 tree is collected and distilled. The dis- 

 tillation produces turpentine and resin. 

 Rosin is also used in the manufacture of 

 the cheaper varnishes and after it has 

 undergone certain treatment it becomes 



Varnish kettles. A coke fire heats them. 

 The gum is melted, then oil is added 



Varnish makers experiment many years to 

 get better mixtures. This is a brush test 



fit for use in varnishes of better quality. 

 All of the raw materials are brought 

 together in the varnish factory and care- 

 fully tested and graded for purity, color 

 and other characteristics. 



How the Varnish Is Made 



The varnish 

 itself is made 

 by melting a 

 quantity of 

 gum in a cov- 

 ered copper or 

 aluminum ket- 

 tle, over a fire. 

 Coke is the fuel 

 usually em- 

 ployed. The 

 varnish maker 

 knows when 

 the gum is suf- 

 ficiently melt- 

 ed, by the way 

 it runs oflf the 

 end of his stir- 

 ring rod. The 

 kettle is re- 

 moved from 

 the fire, and the oil, 

 which may or may 

 not have been 

 previously heated, 

 is added to the 

 melted gum. The 

 cover is removed 

 and the kettle re- 

 turned to the fire. 

 The mixture is then 

 cooked at a de- 

 termined tempera- 

 ture until it has a 

 certain viscosity or 

 "body." The ket- 

 tle is cooled down 

 to a temperature at 

 which it is safe to 

 add the thinners. 

 The next step is the aging of the varnish. 

 Certain varnishes attain their perfect 

 condition only after long months of 

 standing in tanks, where a slow blending- 

 process goes on. This aging gives to the 

 varnish properties that make it last. 

 The varnish has to pass rigid tests for 

 "body" or viscosity, for color, and for dry- 

 ing quality also brushing and flowing tests 

 before it is ready for the market. 



