Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/410

402 To Make Gold Size. Take Gum Animi, Asphaltum, of each 1 ounce, minium litharge of gold and umber, of each $1/2$ ounce, reduce all into a very 'fine powder, and add to them, of linseed oil 4 ounces, of drying oil 8 ounces, digest over a gentle fire that does not flame, so that it may only simmer and bubble up, but not boil, for fear it should run over and set the house on fire. Keep constantly stirring with a stick till all the ingredients are dissolved and incorporated, and do not leave off stirring it till it becomes thick and ropy, and is boiled enough, let it stand till it is almost cold, and then strain it through a coarse linen cloth, and keep it for use. To prepare for use, mix with oil of turpentine during heating, and strain again, add vermilion, and thin as required with turpentine.

Iron-work, Paints for preserving. Plumbago and hot coal tar.

Equal parts of asphaltum and rosin dissolved in common turpentine.

For machinery, dissolve 2 pounds india-rubber, 4 pounds resin, 2 pounds shellac in 5 gallons of benzine. This may be used with any other paint as a vehicle.

Wrought-iron bridges, are painted with white lead as follows: The iron-work is first made clean by scrubbing and brushing it with wire brushes, this done, all the cavities and fissures are filled up with a putty of litharge, linseed oil, varnish, and white lead. This filling being dry, brushing is repeated. Afterwards paint is applied consisting of 300 pounds of white lead, 10 gallons of crude linseed oil, and $1 1/4$ gallons of turpentine. This paint is repeated when the previous coat is sufficiently dry, and finally evenly overspread with white sand. Galvanizing is also employed to prevent rusting. A galvanizing paint consists chiefly of zinc powder and oil varnish. Rusting is further prevented by rubbing the red hot iron with wax, tallow, pitch, or coal tar. Rubbing with heavy petroleum is also well adapted for keeping iron-work clean.