unless actual rusting has started, for it eats into the metal; and some good authorities claim that where it is employed the paint will not adhere as long as it will where hand cleaning alone has been adopted. The use of the sand blast deposits a lot of sand in numerous corners and pockets of the metalwork; and it should all be carefully brushed therefrom before any painting is done.

Application of Paint after Cleaning

The following suggestions concerning field painting, if followed, should lead to economic results in maintenance of bridges:

First. Avoid both cleaning and painting in wet or very cold weather. A few months' delay will seldom do any real harm to the metal or even to the priming coat, unless, perchance, the bridge has been neglected to the extent of actually permitting rusting to start.

Second. Never do much cleaning ahead of the painting, because a spell of bad weather may come on and last so long that such cleaning will have to be repeated. It is not only the extra expense of doing the cleaning twice which is uneconomic, but also the possible injury to the exposed metal from rusting and pitting.

Third. Provide large and safe platforms for both cleaners and painters. It is true that these may be expensive in both first-cost and handling, but their use will enable the workmen to do a much greater amount of work per diem—and better work than if they were not effectively, safely, and comfortably supported. Again, there is to be considered the reduced danger to the lives of the workmen; and as a killed employee generally costs the company $5,000, and an injured one whatever amount he can persuade the company to give him or the court to award, it is certainly economical as well as humanitarian to reduce the danger to a minimum.

Fourth. Give the first field coat a chance to dry thoroughly before applying the next one. In a long structure or a large one, requiring weeks to clean and paint, this restriction will work no economic hardship; but in a short bridge it will, often necessitating the moving of the painting gang to another structure and returning later to apply the second coat.

Fifth. When the amount of cleaning and painting is large, it will be economic to divide the gang permanently into groups of cleaners and painters; but when the bridges are small, or when the total amount of work is not large, all the workmen should be trained so as to become proficient in both of these kinds of labor.

Factors that Affect Results in Painting

As stated by Mr. Houston Lowe, the principal factors that affect results in painting are as follows:

1. Location of the structure, for example, seaboard or inland.

2. Kind and condition of the surface.