16 BULLETIN 1259, U. S. DEPARTMENT OF AGRICULTURE. 
To secure a maximum tliiclvness of paint film upon rivet 
heads, and edges of plat-es, angles or other rolled shapes 
these areas shall be ''striped" in advance of the general 
painting, and shortly afterward shall be given a second or 
"wash" coat when the general coat is appHed. The 
paint shall be well worked into all joints and open spaces. 
Paint shall be thoroughly stirred preferably by means of 
mechanical mixers before being removed from the con- 
tainers, and to keep the pigments in suspension shall be 
kept stirred while being applied. 
All painting must be done in a neat and workmanlike 
manner. 
On all surfaces which are inaccessible for paint brushes, 
the paint shall be apphed \vith sheepskin daubers specially 
constructed for the purpose. 
im'r?^er°Itnt°^ All metal coatcd with impure or unauthorized paint 
shall be thoroughly cleaned and repainted to the satis- 
faction of the engineer, at the expense of the contractor. 
7. Thinning. jf {^ [^ ncccssary in cool weather to thin the paint in 
order that it shall spread more freely, this shall be done 
only by heating in hot water or on steam radiators. 
SHOP PAINTING. 
^8. Shop Clean- ^\\ surfaces of metal to be painted shall be thoroughly 
cleaned of rust, loose mill scale, dirt, oil or grease, and 
all other foreim substances. The removal of rust, scale, 
and dirt shall generally be done by the use of metal 
brushes, scrapers, chisels, hammers or other effective 
means. Oil and grease may be removed by the use of 
gasoline or benzine. Bristle or wood-fiber brushes shall 
be used for removing loose dust. 
ing. ^^°^ ^^^^^' III shop-riveted work all surfaces coming into contact 
when shop-assembled shall each be painted a good shop 
coat thoroughly and evenly applied before assembling. 
These pieces may be assembled ^^ilile the paint is still wet. 
When all fabrication work is complete and has been 
accepted as such, all surfaces not painted before assemb- 
hng shall be painted a good shop coat. Shipping pieces 
shall not be loaded for shipment until thoroughl}^ dry. 
No painting shall be done after loading material on cars. 
markb^^^^'^°° Erectiou marks for the field identification of members 
shall be painted upon previously painted surfaces. 
fliiih^d tiS-?aiS^ With the exception of abutting chord and column 
sphces, column and truss shoe bases, machine-finished 
surfaces shall be coated as soon as practicable after being 
accepted, with a hot mixture of white lead and tallow 
before removal from the shop. Surfaces of iron and steel 
castings milled for the purpose of removing scales, scabs, 
fins, blisters or other surface deformations shall generally 
be given the shop coat of paint. 
The composition used for coating machine-finished 
surfaces shall be mixed in the follo\nng proportions: 
4 pounds pure tallow, 2 pounds pm^e white lead, and 
1 quart pure linseed oil. 
