Mix 5 pounds of iron filings, 1 ounce of sal ammoniac, and 1 ounce of sulphur, and thin the mixture with water.
To tin sheet copper after it has been well cleaned. Take it from the bath. If there are any spots which the acid has failed to remove, scour with salt and sand. Then over a light charcoal fire heat it, touching it with tin or solder, and wipe from one end of the sheet to the other with a handful of flax, only going so fast as it is thoroughly tinned. If the tinning shows a. yellowish color, it shows there is too much heat, which is the greatest danger, as tinning should be done with as little heat as is necessary to make the metal flow. When this is done, rinse off in clean water and dry in sawdust.
To give copper a red appearance as seen on bath boilers. After the copper has been cleaned, rub on red chalk and hammer it in with a planishing hammer.
To tin soldering copper with sal-ammoniac. It will be found very handy to have a stick of sal-ammoniac in the kit for tinning purposes. After filing the heated copper bright, touch the copper with the sal-ammoniac and afterward with a stick of solder. The solder will at once flow over the entire surface. In this there is but one danger, the too great heating of the copper, in which case the burned sal-ammoniac will form a hard crust over the surface. Tin with as little heat as possible. Sal-ammoniac will be found of great value in keeping the soldering copper in shape by frequently rubbing the tinned point with it.
To Keep Soldering Coppers in Order While Soldering with Acid. In a pint of water dissolve a piece of sal-ammoniac about the size of a walnut. Whenever the copper is taken from the fire, dip the point into the liquid, and the zinc taken from the acid will run to the point of the copper and can then be shaken off, leaving the copper bright.