210 PAINT TECHNOLOGY AND TESTS 



inspections will be made, and at the proper time reports will 

 be issued giving the results of the tests. 



" During the painting of the panels considerable interesting 

 data were collected, of which the following is a brief resume: 



11 The hiding power of a paint is one of its most important 

 requisites. It was found in the tests that some oils had the effect 

 of lessening, while others had the effect of increasing the hiding 

 power of the standard pigment formula. This may be due in 

 part to the varying refractive indices of the oils used, as well as 

 to the difference in the quantity of oil required in each test. 

 Some oils were very viscous, while others were very light. 



" The stiff working of heavy-bodied, blown, or heat-oxidized 

 oils, produced films which in some cases gave a very glossy sur- 

 face, even on the priming coat. Some of these resembled var- 

 nished work when finished. It will be of importance to watch 

 these tests carefully for any signs of early breakdown, which 

 might come from too thick a film. The treated Chinese wood 

 oil paints worked rather stiff but produced very smooth films. 

 The rosin oil paints became slightly lumpy on standing, but 

 worked out to a smooth finish somewhat yellowish in color. 

 The marine animal oils, especially the menhaden oil mixtures, 

 dried to a film slightly natter than straight linseed oil. Any 

 odor which was present in the paints made from the animal oils 

 seemed to disappear a few hours after application. The cotton 

 seed and corn oil mixtures made the slowest drying paints, but 

 at the end of the second week of the drying period they set up 

 rapidly to firm films. Soya bean and perilla oils behaved like 

 straight linseed oil, the former being a little slower and the latter 

 slightly more rapid in drying properties. The perilla oil was 

 made from one of the first importations into this country, and 

 was dark in appearance. It made, however, a very easy-working 

 and hard-drying paint. 



1 The oils used in the tests were obtained from reliable sources. 

 After they were received, they were carefully analyzed. The 

 results of the analyses appear in Table I. 



