CONVICT LABOR FOE EOAD WOEK. 141 



PERMANENT FRAME STRUCTURES. 



Structures of tiiis type, similar to that shown in Plate X, figure 2, 

 are used in the concentration or central camps of a few of the south- 

 em counties. In design, they are similar to frame structures used 

 for other purposes, and hence they will be given no special treatment 

 in this bulletin. 



MISCELLANEOUS DATA ON BUILDING MATERIALS. 



Paint. 



The sohd ingredient of paint is called the pigment; and the liquid 

 part, the vehicle. White lead and white zinc are the common white 

 pigments, and the vehicle usually is hnseed oil, with sometimes the 

 addition of a httle turpentine or other volatile solvent. 



These are compounds of lead and manganese dissolved in oil, and 

 this solution thinned with turpentine or benzine. They act as car- 

 riers of oxygen from the air to the oil, and their addition to a paint 

 makes it diy more rapidly. Not more than 10 per cent by volume 

 of a drier should be added to oil. 



PREMING COAT. 



This is the first coat applied to the clean surface. The priming coat 

 for wood usually is made by thinning a gallon of ordinary paint with 

 a gallon of raw linseed oil. In all woodwork, nail holes and other 

 defects should be filled with putty after the priming coat has been 

 applied; but if the wood be resinous, knots and resinous places 

 should be covered with shellac before the priming coat is put on. 

 Pitchy woods, such as southern yeUow pine and cypress, do not 

 absorb oil readily, and turpentine should be substituted for part of 

 the oil. 



SECOND AND THIRD COATS. 



The priming coat, having been absorbed largely by the wood, a 

 second, and possibly a third, coat of paint should be applied. The 

 most common paint used on houses is white lead. This is commonly 

 sold as paste white lead containing 8 per cent of oil, 100 pounds 

 being equal to 2.8 gallons in volume, and it is commonly mixed with 

 3 1 gallons of raw linseed oil, 1 quart of turpentine, and 1 pint of 

 drier to make 6§ gallons of paint for the second coat, or with 4 gal- 

 lons of oil, 1 pint of turpentine, and 1 pint of drier for the third coat. 

 If a vehicle composed of half linseed oil and half turpentine be used 

 in the paint for the second coat, it will have the effect of making the 

 paint dry with a duU or "flat" surface instead of a glossy surface, 

 and the third coat will adhere better. If white zinc is used, 9i 

 pounrls of dry zinc oxide and 0.57 gallon of oil make 1 gallon of paint; 



