Copper Flashings - A Manual - 1925 - Page 57
Copper may be given different finishes by the use of various chemicals. The most commonly known and used of these are set forth below.
The Research Staff of the Copper and Brass Research Association will be glad to advise those who desire special finishes.
1. Bronze or Brown.
Clean off all dirt and traces of acid or other flux carefully. Give the cleaned copper a thorough coating of boiled linseed oil. Touch up the seams with copper bronze.
This can be applied with a mop or brush or with rags. This treatment makes the copper turn a dark brown color somewhat similar to old bronze.
How long this color will last, especially near salt air, is problematical. There are examples of it six or more years old. It is best to renew the treatment every two or three years unless the atmosphere is generally clear and dry. By this means it is possible, after a few treatments, to retain the color permanently.
A more elaborate method is:
Clean the copper thoroughly with a strong soda solution (4 to 6 ounces per gallon of hot water) or with fine pumice and kerosene and then wipe it off with gasoline.
Apply with a brush a solution of 1 oz. of liver of sulphur in one gallon of lukewarm water.
After the desired color has been obtained wash the solution off with water.
The above formula should be first tried out on a small piece of copper. If the color obtained the first time is not satisfactory it may be advisable to give a second coating of the solution.
2. Green: Verdigris; Copper Patina.
Clean the copper thoroughly with a strong solution (4 to 6 ounces per gallon) of soda in hot water. Wash this off with clean hot water.
Apply with a brush a solution of ½ lb. of salt to 2 gals. of hot water. Let stand for one day and then sprinkle the surface with clean water.
It is absolutely necessary for good results that all the grease and oil of the manufacturing process be removed from the copper. The strong soda solution will do this. Uniform finish will not be obtained unless the copper is thoroughly cleaned.
Copper left to the action of the atmosphere will eventually turn green, the color of copper carbonate. It first darkens, then becomes a dull black (the oxide); finally the oxide changes to the carbonate which is the well-known patina of copper. This carbonate is a protective coating and should not be removed.
It is difficult to obtain a good bond between paint and copper. This is due to the grease and oil of the manufacturing process which is rolled into the fine pores in the surface of the sheets.
Paint applied directly to untreated copper will not stand for any length of time, particularly when exposed to the weather. The surface must be thoroughly cleaned and roughened before the paint will adhere.
This may be accomplished by washing the copper with a solution of 4 ozs. of copper sulphate in one-half gallon of luke warm water in a glass or earthen vessel, to which is added one-eighth ounce of nitric acid. If the surface is still very smooth, additional roughening must be done by abrasives.
Before painting, the surface must be carefully washed with clean water to remove the last trace of the solution and the paint must not be applied until the surface is thoroughly dry.
Three coats of paint will give the best results. The first coat should be composed of 15 pounds of red lead to one gallon of raw linseed oil with not more than ½ pint of oil dryer. The last two coats should be composed of 15 pounds of white lead to 1 gallon of raw linseed oil with not more than 5 per cent. of oil dryer and the necessary color.
PROPORTIONING GUTTERS AND LEADERS
The chief consideration in designing gutters and leaders is to conduct the water running off a roof quickly and easily away. To do this it is essential that (1) the gutter be large enough to conduct all the water to the outlet; (2) the outlet be large enough to accelerate the velocity of the water in the gutter when it enters the outlet.
It is obvious that more water will drop through
- 57 -