EFFECTS OF PAINTING 121 



References : 



1. 1304 : 42. The Protection Due to Paint. 



2. Forest Service Circular 139. A Primer of Wood Preservation. 



a. 1706 : 361-362. Preparation of White Paint. 



b. 1708 : 379. Preparation of White Paint. 



c. 1709 : 356-358. Preparation of White Paint. 



d. 1712 : 34. The Reason Why Paints Dry. 



e. 1712 ; 352-355. Paints and Painting. 



Experiment 47. The Testing of Paint. 



Apparatus : Burner, blowpipe, piece of charcoal for blow- 

 piping, six beakers 100 c.c., small paint brush. 



Materials : Basic lead carbonate, red lead, litharge, whiting, 

 barium sulphate, zinc oxide, linseed oil, fish oil, kerosene oil. 



a. Make a little hollow in the charcoal and place a small 

 amount of white lead in it. Then direct the blowpipe flame 

 against the white lead so that half of the flame plays on it. 

 This reduces the white lead to metallic lead. Repeat with 

 red lead and litharge. More rapid results may be obtained 

 with these by mixing an equal amount of ground charcoal 

 with each before blowpiping. 



6. Repeat (a) with zinc oxide and then with barium sul- 

 phate. What results do you obtain ? Could you distinguish 

 a lead compound from zinc oxide and from barium sulphate ? 

 These are the chief adulterants of paint. 



c. Expose, in separate dishes, linseed oil, fish oil, and kero- 

 sene oil for twenty-four hours. What is the result? Which 

 would protect wood the best ? What is the harm of allowing 

 paint to remain unused for some time? 



d. Mix a little white lead in each of the oils and see which 

 gives the best blend. Paint a board with each kind of 

 " paint " and note the spreading ability of each. 



e. Using linseed oil, mix a little zinc oxide, paint the board, 



