Home › Adhesives, Paints, and Varnishes › Adhesives, Paints, and Varnishes: Venetian

Adhesives, Paints, and Varnishes: Venetian

Sandarac is used to impart hardness, mastic to give a gloss. Venetian turpentine is frequently added to sandarac, or a little concentrate ammonia is often added to overcome the tendency of varnish to chill or crack and give a rough surface. Venetian turpentine is used with sandarac to prevent excessive brittleness.

To make spirit varnishes, first pulverize the resins and mix them with sand or broken glass to prevent their forming into lumps. Put them in a double boiler, cover with the spirit, which should be not less than 95 per cent pure, and dissolve with gentle heat. Afterwards filter, first through silk, then through filter paper.

Shellac Varnishes. - Shellac will be more soluble if powdered and exposed to the air as long as possible before using. To make cheap shellac, dissolve 1 ounce of borax in 8 ounces of boiling water. Add 5 ounces of pulverized shellac, stir, and boil until dissolved. If too thin, continue to boil until sufficient water has evaporated, or if too thick, thin with boiling water. This solution is equal to spirit varnishes for many purposes, and is much cheaper. When dry, weather has no effect upon it. Hence it is useful to dissolve water colors for calcimining and for other purposes.

Or India ink rubbed up in this solution may be used where an acidproof labeling ink is required. It is not affected by the fumes of acids.

Or put in a glass fruit jar 8 ounces of water, 3 ounces of white shellac, and 1 ounce of sal ammoniac, and let stand over night. Place the fruit jar in a saucepan containing hot water, and boil, stirring constantly until the shellac is dissolved.

Or boil in an earthen vessel.

This solution may be used as a substitute for spirit varnish, is much cheaper, and has the advantage of being waterproof. Diluted with 10 or 12 parts of water and applied by means of a brush, it may be used for waterproofing cloth or making oilcloth. It may also be used for staining and waterproofing wood, as a stain paint or a varnish, according to consistency, and may be mixed with any water-color or cil pigments to produce any color that may be desired.

The above are not true spirit varnishes, but may be treated most conveniently in this place. Or dissolve 10 ounces of white shellac in 1 quart of 95 per cent alcohol. This may be done without heat by pouring the alcohol over the shellac and letting it stand in a warm place until dissolved. Keep in a covered fruit jar or corked bottle to prevent evaporation. This is a good transparent varnish for furniture, woodwork, tools, and most other purposes. It dries rapidly. It is especially useful to coat woodwork that is exposed to the weather, as farming tools and other utensils that are frequently used or left out of doors. It is a very convenient and serviceable all-round varnish. Or color the above by the addition of lampblack or asphaltum. This gives a glossy black varnish.

Or, to give a thicker coat of varnish, take 1 quart of 95 per cent alcohol, and add all the gum shellac it will cut. Strain out the excess through silk and filter paper. Add 2 ounces of Venetian turpentine. This gives a transparent gloss.

Or color with aniline dyes as desired.

Or, to make a hard shellac varnish for special purposes, as gunstocks and the like, dissolve 10 ounces of shellac, 1 ounce of sandarac, and 1 dram of Venetian turpentine in 1 gallon of 95 per cent alcohol. Put in a glass fruit jar or earthenware vessel, cover tightly, and let stand in a warm place until dissolved. Apply two or three coats, and finish, if desired, with one or two coats of still harder varnish, prepared as follows:

Dissolve 1 ounce of shellac, ounce of sandarac, and ounce of Venetian turpentine in 2 quarts of alcohol. This gives a high polish and requires less rubbing.

To Color Shellac. - Add 1 ounce of aniline dye to 1 pint of shellac varnish.

For mahogany, use aniline cardinal dye.

Other colors and coloring matters may be added freely to produce any colors desired.

Or mix equal weights of gum shellac and alcohol, and heat until the mixture becomes quite thick. Add any desired amount of aniline dyes dissolved in alcohol, and thin with about one fifth by weight of castor oil.

Lacquers.-Colored spirit varnishes are used to give a tinge of gold to articles made of brass or other base metals. The bases of these lacquers is a varnish consisting of 2 parts of seed-lac and 4 parts of sandarac or elemi dissolved in 40 parts of alcohol.

To this, tinctures of annotto, coralline, dragon's blood, gamboge, gummigutta, Martius yellow, picric acid, or turmeric are added separately to give the required color.

To make a good gold lacquer for brass work, dissolve 3 ounces of seedlac, 1 ounce of turmeric, and 1 ounce of dragon's blood in 1 pint of alcohol. Put the solution in a glass fruit jar and let stand in a warm place, shaking frequently until dissolved.

Filter through silk and filter paper.

Or, if deep gold is desired, dissolve pound of ground turmeric, ounce of gamboge, 1 pounds of sandarac, and 6 ounces of shellac in 1 gallon of 95 per cent alcohol. Strain through silk and filter paper and add pint of turpentine varnish.

Or, for deep red, dissolve 1½ pounds of annotto, pound of dragon's blood, and 14 pounds of gum sandarac in 1 gallon of alcohol. Strain, filter, and add 1 pint of turpentine varnish.

Or, for pale gold, dissolve 1/2 ounce of gamboge, 1½ ounces of cape aloes, and pound of white shellac in 1 gallon of alcohol.