LINSEED OIL. 11 



PAINT MATERIALS. 



LINSEED OIL. 

 1. Preparation of Sample. 



All tests are to be made on oil which has been filtered through paper at a 

 temperature of between 15 and 30 C. immediately before weighing, with the 

 exception of tests No. 0, Turbidity; No. 7, Foots; No. 9, Moisture and Volatile 

 Matter, and No. 10, Ash. The sample should be thoroughly agitated before the 

 removal of a portion for filtration or analysis. 



2. Specific Gravity. 

 Determine with a pyknometer, plummet, or hydrometer at 15.5 C. 



3. Viscosity. 



Use the Engler-Ubbelohde method, making the determination at 20 C. 

 4. Flash Point, Open Cup. 



Set a nickel crucible 60 mm in diameter at the top, 40 mm in diameter at the 

 bottom, and 60 mm in height in a hole in the middle of a sheet of asbestos 

 board 200 mm square. The bottom of the crucible should project about !'." mm 

 through the asbestos. Support the asbestos on a tripod and suspend a ther- 

 mometer reading to 400 C. in degrees in the center of the crucible, so that the 

 lower end of the thermometer is 10 mm from the bottom of the crucible. Then 

 pour in the oil until its level is 15 mm below the top of the crucible. Place a 

 Bunsen burner below the crucible and regulate the size of flame so that the 

 thermometer rises 9 a minute. As a test flame use an ordinary blowpipe 

 attached to a gas tube. The flame should be about 6 mm long. Begin testing 

 when the temperature of the oil reaches 220 C., and test for every rise of 

 3. In applying the test move the flame slowly across the entire width of the 

 crucible immediately in front of the thermometer and 10 mm above the surface 

 of the oil. The flash point is the lowest temperature at which the vapors above 

 the oil flash and then go out. 



5. Fire Point. 



After noting the temperature at which the oil flashes continue the heating 

 until the vapors catch fire and burn over the surface of the oil. The tempera- 

 ture at which this takes place is the fire point. In determining the flash point 

 note the behavior of the oil. It should not foam or crack on heating. Foam- 

 ing and cracking are frequently caused by the presence of water. 



6. Turbidity. 

 Note whether the oil is perfectly clear or not. 



7. Foots. 



Let a liter of the oil stand in a clear glass bottle for eight days, and then 

 note the amount of sediment formed. The highest grades of oil show no turbidity 

 or foots by this test. The claim is made that sometimes what would be called 

 foots by the above method is due to the freezing out of fats of rather high melt- 



