Slating for Blackboards.

The Manufacturer and Builder 6, 1894

There are quite a number of ways of doing this class of work. The great secret in putting up a good blackboard is to use no oil of any desciption in any of the coats. If it is a plastered or papered surface you widh to slate, first give it a coat of glue size, then rub it down lightly with fine sandpaper, then give it a coat of shellac varnish and lampblack enough to give it a fair body. If on wood, omit the sizing. Then give two coats of either of following:

1. Two quarts of alcohol, ½ pounds of shellac, 12 drachms lampblack, 20 drachms ultramarine blue, 4 ounces powdered Rochelle salts, 6 ounces powdered pumice stone.

2. One gallon alcohol, 1 pound shellac, ½ pound ivory black, 5 ounces emery flour, and 4 ounces ultramarine blue.

3. Take equal part of pumice stone and red lead, and grind them in a mixture of turpentine and best varnish; add enough lampblack to make a dark color, then thin with turpentine until it is perfectly flat. Apply with a brush and blend over.

4. One gallon wood naphtha, 1 pound shellac, 4 ounces of lampblack, 4 ounces ultramarine blue, 1½ pounds soft water, 2 ounces pumice, stone and powdered emery. The wood naphtha is cheaper than alcohol, and does as well.

5. One gallon shellac varnish, 4 pounds black manganese, 2 pounds soft water.

All the above must be kept well stirred while using them, and when you are through put what you have in a bottle and cork it up, and it will keep for a long time. If, at any time, the sisting is too thick, thin with alcohol.

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