Soap and water are poor materials with which to wash greasy and dirty shop windows. The labor cost is excessive; the soapy water gets into the joints of the window sashes and hastens decay; and there is liable to be a good deal of soapy water slopped over benches, tools and machines. The quick way, the economical way, and the good way, is to use the following preparation, which has been used by the writer with good success and satisfaction for the past ten years. Dilute alcohol with three times its bulk of water. Stir into this whiting enough to thicken it somewhat. Apply this to the glass with a cotton cloth or waste. Leave it fifteen or twenty minutes to dry. Then rub off with a cotton cloth or a handful of waste. If sashes are to be painted, there will be no need of a long wait for the wood to dry, as the alcohol will very much hasten the evaporation of the water and leave the woodwork in fine condition for the painter.
Peabody, Mass. Oscar E. Perrigo.
The article should first be dipped in a caustic soda or caustic potash solution -potash preferred - then thoroughly washed in clear water and dipped in a bath of concentrated nitric acid, after which it should be thoroughly washed and dried in hot sawdust. The caustic solution should be prepared in a tank provided with a steam coil and should test with Baumes' hydrometer at anywhere between 20 and 30. The length of time an article should remain in the caustic solution is a matter of judgment. The solution should attack the aluminum rapidly, and upon removing the article from the solution, the solution should boil furiously on the metal. After washing, the articles should show a very black color, which turns to a silvery white finish upon dipping in the nitric acid. The best temperature for the caustic solution is at 200 degrees F., just below the boiling point. By the use of a steam coil the solution can be kept at an even temperature, and the strength of the solution can be maintained by adding small quantities of caustic from time to time. The temperature and strength of the solution are very important.
The principal point to bear in mind in washing and drying is to dry without streaks. which is accomplished if the sawdust contains no pitch or rosin.
This finish can be improved by scratch-brushing the article before dipping or by first dipping in the two solutions and then scratch-brushing and afterward dipping again. The scratch-brushing destroys the grain of the metal and reduces the possibility of the article drying with streaks.
Bridgeport, Conn. S. H. Sweet.
To quickly prepare fine abrasive use FFF emery or "15-minute" carborundum with benzine or naphtha for a liquid, mixing them in a square bottle. Use about two ounces of the abrasive to one quart of liquid; shake well and then lay the bottle flat on its side for the number of minutes needed to settle; then pull the cork and let the liquid flow out until level with the cork hole bottom. The liquid just drawn off can be used at once with a brush, but by allowing it to stand for a time, the top portion can be poured off, leaving the abrasive with a little benzine which will evaporate quickly, and leave the clear powder.
In explanation of the term "15-minute" carborundum, would say that this is a term applied to fine abrasive obtained by the process just explained (manufacturers, of course, using water-tanks instead of bottles), the time the liquid is allowed to stand, in minutes, being used to distinguish it. Thus, if it stands 15 minutes it will be known as 15-minute abrasive, etc.