TWELFTH ANNUAL YEAR BOOK— PART X 511 



zinc lead, and lithopone are practically the only white pigments which 

 have good covering power in oil. These pigments are all rather ex- 

 pensive, and as they are heavy it takes quite a large amount to make a 

 paint. 



Of the dark shades, there are a number of cheaper pigments which have 

 very good covering power. It may be quite safely stated that for a white 

 paint that really covers, some one or more of the white pigments just 

 enumreated must be used. For a dark brown, however, a good covering 

 can be obtained with an iron oxid pigment, which is very much cheaper. 

 Therefore, for such paints there is no reason for using an expensive lead 

 or zinc pigment, 



ESTIilATED COST OF WHITE PAIXTS. 



A vehicle for outside paint of the best quality will generally consist 

 of from 90 to 95 per cent of linseed oil and from 10 to 5 per cent of japan 

 drier. A good japan drier has about the same specific gravity as linseed 

 oil, and each may be considered to weigh about 1% pounds to the gallon. 

 Of course, the prices of all paint materials vary, but at the present time 

 linseed oil sells for approximately 90 cents a gallon, and a good grade 

 of japan can be bought for $1.60. . In making up paints, the drier should 

 be mixed with the larger portion of the oil before adding the pigment. 

 Using the prices and weights just given for linseed oil and japan drier, 

 the liquid portion of a paint will cost about 95 cents a gallon, or 12 14 

 cents a pound. White lead, both dry and in the form of paste, costs ap- 

 proximately 7 cents a pound, zinc white approximately 8 cents a pound, 

 and the other white pigments which cover well will not differ very much 

 from these two in price. A gallon of white lead paint will weigh from 21 

 to 22 pounds. Fourteen pounds of dry white lead and l\i pounds of 

 vehicle will make a gallon of paint and at the prices quoted the cost 

 would be about ?1.87; 15 pounds of paste lead and QVi pounds of vehicle 

 will make a gallon of paint, costing $1.82; 91/2 pounds of white zinc and 

 5% pounds of the paint vehicle will make a gallon of zinc white paint cost- 

 ing about $1.46. 



Of course, these prices are based on an assumed cost for the ingredients, 

 and to make an exact estimate it would be necessary to know the exact 

 prices of the different materials entering into the paint. Many painters 

 insist that a paint composed entirely of white lead, linseed oil, and drier 

 is the best. Others contend that a mixture of white lead and zinc white 

 is the best, and still others say that a mixture of these pigments with 

 the cheaper white pigments which have slight covering power makes a 

 better paint than the expensive pigments alone. It is probably true that 

 a. mixture of lead and zinc is superior to either pigment by itself, and 

 also that the addition of a small amount of so-called inert pigments (silica, 

 whiting, Barytes,china-clay, etc.) has no injurious effect on the paint 

 and may even be beneficial. The addition of a large amount, however, 

 of such pigments will give a paint deficient in covering power, and the ad- 

 dition should have the effect of cheapening the product. There is no 

 reason why any mixed paint should cost per gallon more than a paint made 

 entirely of white lead, oil, and the necessary drier. By ascertaining the 



