3. Quality of the paint and its temperature.

4. Workmanship of the painter.

5. Number of coats applied and their sequence.

6. Time allowed to elapse between coats.

7. Atmospheric conditions when painting is done.

By giving all these factors due consideration when handling a job of bridge painting, and by striving in every way to accommodate the work in the best manner possible to the governing conditions, one can often effect a decided economy.

Economic Observations Concerning Painting in General

The price of paint is a matter which seldom needs much consideration from the economic standpoint, unless when debating on the choice of two or three kinds of nearly equal quality; because painting is so much more expensive than the paint itself that a very little extra life of the coatings will out-weigh in economic importance a large difference in the cost of the material. Generally, one should determine what kinds of paint would probably be the best for any job, then pay for them whatever is necessary, unless it should occur that the seller is extortionate in his demands, which is not likely to be the case when dealing with first-class business men.

It does not pay to dicker about the price of paint, because the manufacturer is accustomed to "cutting his coat according to his cloth." The author remembers a glaring case of this reprehensible trick that occurred in the nineties. He had been using very satisfactorily a certain magnetic-iron-oxide paint that was not expensive, and recommended it to a contractor-friend of his for an elevated railroad line. Some three years later the paint agent dropped into the author's office and asked him to specify the brand in question for a large piece of work then about to be let. The request was refused—much to the surprise of the agent, who exclaimed " is not our paint that you used on the Blank City train-shed giving good service after four years of use?" The reply was: "Yes; but how about the condition of your paint on the elevated railroad in the same locality—is it not already going to pieces with only two years' service?" In answer to this question the agent had to explain that the Contractor had jewed down the price and, therefore, the paint had to be adulterated in order to meet the cut. Thereupon the author refused to have any more dealings with such a dishonest manufacturing company, and never again adopted the said paint on any of his metalwork.

A layer of good paint is about three times as thick as a layer of the linseed oil in which it is mixed, and the increase in thickness of the former is in direct proportion to the fineness of the pigment; hence it is economic to have the said pigment ground as fine as possible, for it is a fact that, with the same  weight  of  oil  and  the  same  weight  of  pigment,  the greater the