To Make the Flux. Purchase at the drug store ten cents' worth of crude muriatic acid. Place this in a porcelain, stone or glass jar. Add as much zinc in small pieces as the acid will thoroughly dissolve. The flux is always best when it has stood from twelve to sixteen hours before using. Strain through a piece of cloth or muslin. Dilute with a little water, about half and half. This will make the soldering flux. When using keep the flux well mixed and free from dust and dirt.
Tinning Capping Iron. Purchase five or ten cents worth of sal ammoniac at the drug store; clean iron with file or knife. Mix a little solder with the sal ammoniac. Heat the capping iron hot enough so that it will melt the solder and convert it into a liquid. Place the iron in the vessel containing the mixture of sal ammoniac and solder. Rotate iron in the mixture until the soldering edge of the iron has become bright or thoroughly covered with the solder. All particles of smudge, burned material, and so forth, should be removed from the iron before tinning.
Tinning the Tipping Copper. The tipping copper is tinned in very much the same way as the iron. Sometimes it is desirable to file the tipping copper a bit so as to make it smooth and to correct the point. Heat the copper and rotate the tip of it in the mixture of sal ammoniac and lead until it has been covered with the melted lead and is bright as silver. The copper should be filed nearly to a sharp point.
Capping a Tin Can. Use one tin can for experimenting. By capping and tipping, heating the cap, and throwing it off and simply putting another cap on the same can, you can use this one can until you become proficient in capping.
When capping the full packs arrange the cans in rows upon the table while the capping and tipping irons are heating in the fire. Take a handful of solder-hemmed caps and place them on all cans ready to be capped. Place a finger on the vent hole, hold cap in place, and run the brush containing a small amount of flux evenly round the solder-hemmed cap with one stroke of the hand. Do this with all cans ready to be capped. Then take the capping iron from the fire. Insert in center the upright steel. Hold the capping iron above the cap until the center rod touches the cap and holds it in place. Then bring it down in contact with all four points of solder-hemmed cap and rotate back and forth about three strokes. Do not bear down on capping iron. A forward and back stroke of this kind, if properly applied, will perfectly solder the cap in place. Remove capping iron and inspect the joint.
If any pin-holes are found recap or repair with copper. It may be necessary to use a piece of wire lead or waste lead rim from a cap to add more lead to the broken or pinhole places of a cap.
Tipping a Tin Can. Take flux jar and brush. Dip brush lightly in flux and strike the vent hole a side stroke, lightly, with brush saturated with flux.
Use the waste solder-hemmed cap rim or wire solder. Place point of wire solder over vent hole. Place upon this the point of the hot, bright, tipping copper. Press down with a rotary motion. Remove quickly. A little practice will not only make this easy, but a smooth, perfect joint and filling will be the result. The cans are now ready for the canner. The handwork is all over, for the canner will do the rest.
Precautions. Do not fill tin cans too full. Leave a one-eighth to one-quarter inch space at the top of the can and see that the product does not touch the cover. If any of the product touches the cover the application of the hot iron produces steam, which may blow out the solder, making it impossible to seal the can.
RULES FOR STERILIZING