copper, reinforced for strength and stiffness with steel sections. Copper and steel shall be insulated by strips of 3-pound lead or by an asbestos covering on the steel. All sash bars and bearings for glass shall have condensation gutters leading to the outside of the skylight. All skylights shall be made water- and weather-tight with joints interlocked, riveted and soldered, and shall conform to the requirements of the National Board of Fire Underwriters. Duplicate sets of detail drawings shall be submitted for approval.

50. Cornices. Where shown on the drawings cornices shall be erected of 20-ounce hard (cornice temper) copper. They shall be made in strict accordance with the profiles shown on drawings with moldings true, sharp and straight. All flat surfaces over 5 inches wide shall be crimped, all mitres and joints carefully fitted, angles and corners reinforced, and all joints neatly riveted and soldered together and made water-tight. Cornice work shall be reinforced with properly-shaped steel brackets, separated from the copper by 3-pound sheet lead.

   The top edge shall be formed over a heavy brass or bronze edge-strip or drip properly shaped to permit the joining of the top flashing or gutter-lining as specified elsewhere.

   Ornaments shall be stamped in soft (roofing temper) copper with dies made from approved models.

   Duplicate sets of detail drawings shall be submitted for approval.

51. Copper-covered Walls. On vertical walls marked "Copper," such as bulkheads, skylight curbs, penthouse walls, etc., erect standing seam or paneled surfaces as indicated. All standing seam work shall be fastened to wall surfaces with cleats nailed with copper nails to wood sheathing, or furring strips. All paneled work shall have casings or strips to receive copper. Crimped sheets shall be used for all large panels and large areas of plain surfaces.

52. Cleaning Copper. Except as otherwise specified all copper to be colored or painted shall first be thoroughly cleaned by scrubbing with a strong solution of caustic soda m hot water. After this solution has been applied the copper shall be washed off with clean water.

53. Coloring Copper. (-1.) GREEN PATINA. After the copper has been scrubbed clean the following solution shall be applied: (1) One pound of powdered sal ammoniac to 5 gallons of water. Dissolve thoroughly and let stand 24 hours. Apply with a brush, covering every part. Let stand one day and then sprinkle with clean water; or, (2) one-half pound of salt to 2 gallons of water. Apply as for (1) above.

   (-2.) BROWN OR BRONZE. Clean the copper of all foreign substances and debris and rub it thoroughly with waste soaked in boiled linseed oil until the desired color is obtained. Touch up solder with copper bronze.

54. Painting Copper. All copper work to be painted shall first be scrubbed clean as specified elsewhere and coated with a wash composed of copper sulphate, 4 ounces to ½ gallon of lukewarm water, and ⅛ ounce of commercial nitric acid. This wash shall be applied with a brush, and allowed to dry. The copper shall then be dusted with a dry brush, and given one coat of red-lead-and-oil paint and two coats white-lead-and-oil paint, composed of 15 pounds of red lead to 1 gallon of raw linseed oil, with not more than ½ pint of oil drier. All subsequent coats shall be composed of 15 pounds of white lead to 1 gallon of raw linseed oil with not more than 5 per cent. of oil drier and the necessary color to give the desired tint. All painting materials shall be of the quality specified under "Painting and Varnishing.” Only those surfaces of copper work that will be exposed after installation shall be painted.

- 20 -