blackboard wash - blackboard wash (liquid slating); blackboard wash - See also painting.
4 pints 95 per cent, alcohol, 8 oz. shellac, 12 dr. lampblack, 20 dr. ultramarine blue, 4 oz. powdered rotten-stone, 6 oz. powdered pumice.
1 gal. 95 per cent, alcohol, 1 lb. shellac, 8 oz. best ivory black, 5 oz. finest floor emery, 4 oz. ultramarine blue. Make a perfect solution of the shellac in the alcohol before adding the other articles. To apply the slating, have the surface smooth and perfectly free from grease; well shake the bottle containing the preparation, and pour out a small quantity only into a dish, and apply it with a new flat varnish brush as rapidly as possible, Keep the bottle well corked, and shake it up each time before pouring out the liquid.
Lampblack and flour of emery mixed with spirit varnish. No more lampblack and flour of emery should be used than are sufficient to give the required black abrading surface. The thinner the mixture the better. Lampblack should first be ground with a small quantity of spirit varnish or alcohol to free it from lumps. The composition should be applied to the smoothly-planed surface of a board with a common paint-brush. Let it become thoroughly dry and hard before it is used, Rub it down with pumice if too rough.
½ gal. shellac varnish, 5 oz. lampblack, 3 oz. powdered iron ore or emery; if too thick, thin with alcohol. Give 3 coats of the composition, allowing each to dry before putting on the next; the first may be of shellac and lampblack alone.
½ lb. logwood and sufficient boiling water to cover it; allow it to stand for twenty-four hours. Strain, and allow the solution, boiling, if possible, twice, allowing the board to dry in the interval. Then dissolve ¼ lb. of copperas in about 1 pint of boiling water, and apply it boiling, once or twice, according to the degree of blackness obtained. Before using it, rub it over well with rushes, straw, ferns, or shoemakers' heel ball. It may be a little difficult to rub the chalk off at first, but after a fortnight's use that will disappear. Use unprepared chalk, which writes well.
Heat ¼ lb. lampblack on a flat piece of tin or iron on a fire till it becomes red, take it off, and leave it until sufficiently cool, when it must be crushed with the blade of a knife on a flat board quite fine; then get ½ pint of spirits of turpentine, mix both together, and apply the mixture with a size brush. If the board is new, it would be well to give it one or two coats of lampblack - not burnt, but mixed with boiled oil - adding ½ lb. of patent driers. After the board is thoroughly dried, apply the burnt lampblack and turpentine. The preparation must be laid on quickly.
Dissolve 4 oz. shellac in 1 qt. alcohol; add lampblack, 6 dr.; ultramarine blue, 1 dr.; pumice stone, powdered, 3 oz.; rotten-stone, powdered, 2 oz. Have the board dry and free from grease before painting it.
To make 1 gal., take 10 oz. pulverised and sifted pumice, 6 oz. powdered rotten-stone, ¾ lb. good lampblack, and alcohol enough from 1 gal. to form, with these, a thick paste, which must be well rubbed and ground together. Then dissolve 14 oz. shellac in the remainder of the gal. of alcohol by digestion and agitation, and finally mix this varnish and the paste together. It is applied to the board with a brush, care being taken to keep the paint well stirred, so that the pumice will not settle. Two coats are usually necessary. The first should be allowed to dry thoroughly before the second is put on, the latter being applied so as not to disturb or rub off any portion of the first. 1 gal. of this paint will ordinarily furnish two coats for 60 sq. yds. of blackboard. When the paint is to be put on plastered walls, the wall should be previously coated with glue size - 1 lb. glue, 1 gal. water, enough lampblack to colour; put on hot.