off the joints and the extra time in getting the proportions of tin and lead right in melting is taken into account, and added to the fact that the solder will not be so good as if made from all ingot tin imd lead, the odds of profit and loss are against the practice. Solder of this class fuses at about 440° F. Fine solder has proportions of half tin and half lead, fusing at 370'. It can be tested by pouring out in flat strips, and when cool, bending it close to the ear, it should emit a very slight creaking sound. If the creaking be too marked, it is too fine. <Callout type="tip" title="Pro Technique">Fine solder fuses at 370° F.</Callout> PLUMBERS' MATERIALS. 467 Fine blow-pipe solder is made of 1^ parts of tin to 1 of lead, fusing at 334''. It is run out on a clean slab, in long strips, about a quarter of an inch in diameter, from a ladle having a small bole drilled in tbe spout to get the size even. A slight addition of bismuth renders solder extra fusible. Solder is injured by impurities. Zinc will make it too brittle to work at all, and the solder must then be purified by burning the zinc out, letting the pot get nearly red-hot, till the zinc burns off in vapour and scum, and skimming it, but not stirring up the lead while red-hot. Add a little sulphur, which will bring up more scum, which remove. Let solder cool, adding tallow, and mixing it up when nearly cool enough to work with, adding also a little resin and pure tin. Solder should be stirred by the plumber in the pot always before taking a ladleful out, as the lead and tin are apt to lie in layers, owing to difference in specific gravity. Plumbers' students should practise carefully the effects produced on their solders by adding lead €md tin in various proportions. The teacher should assist them in class with practical advice, and, pointing out the effects, explain the causes. Plumbers do not gain by complaining of the quality of solder served to them ; they should know how to adjust it themselves. Keep zinc at a respectful distance from your solder. In making alloys like solder the melting-pot should be red-hot (a white heat is better), and those metals placed in it which require the most heat to fuse them. Put the metals in the melting-pot in strict order, following exactly the different fusing-points from the highest degree of temperature required down to the lowest, in r^ular sequence, and being especially careful to refrain from adding the next metal until those already in the pot are completely melted. When the metals fused together in the crucible require 468 DOMESTIC SANITARY DRAINAGE AND PLUMBING. very different temperature to melt them, a layer of charooal should be placed upon them; or, if there is much tin in the alloy, a layer of sand should be used. The molten mass should be vigorously stirred with a stick, and even while pouring it into another vessel the stirring shoidd not be relaxed. Another hint is to use a little old alloy in making new, if there is any on hand, and the concluding word of caution is to make sure that the melting-pots are absolutely clean and free from any traces of former operations. Plumbers' smudge is of some importance in making joints. The ugly, unfinished appearance of joints so often observed is frequently caused by the use of badly made smudge. Some plumbers consider the quality of the smudge they use as beneath their notice, but it is only by careful attention to such details in plumbing work that neat and sound workmanship is attained. <Callout type="important" title="Critical Rule">Smudge must be carefully prepared for a clean finish.</Callout> Good smudge will dry quickly of a dead black shade, contrasting well with the bright grey shade of lead. When dry it will not rub off easily, nor will it chip or peel off, and it will not be sticky or greasy. Good smudge is made by mixing carefully one part by weight of chalk and two parts of lampblack, grinding them well together with a pestle in a small cast-iron mortar, or on a slab with a palette knife, then adding a little melted size, and mixing all into a paste. Now take the smudge-pot, half fill it with equal parts melted size and water, pour in the paste, stirring all carefully, and warm up the whole in a glue-pot on a fire or stove, thus not allowing the temperature to rise quite to 212° F., the boiling-point. <Callout type="warning" title="Safety Hazard">Avoid overheating smudge pot.</Callout> As the quality of the materials will vary, the smudge when made should be tested in the following way: Take a piece of sheet lead, previously cleaned, and apply the smudge evenly with a paint-brush; then dry it at the fire. Then gently rub the smudge to see if it adheres firmly. If it rubs off, more size must be added. If it chips or peels off, water must be added, and all heated again, continuing the tests till the smudge is found right for working. Porter, sometimes added to smudge, renders it sticky, and is not recommended. Fluxes are used to assist the flow of melting metals, and are specially useful to plumbers in soldering operations. When metals are in process of heating or melting they are liable to attack from the air, which coats them with a covering of oxide, checking the fusion of the metal and preventing combination as an alloy. This effect may be observed in the scale which forms on copper in soldering irons, and in the dross which floats on molten lead or solder. Fluxes are used chiefly to stop the formation of this oxide or rust, by excluding the air from the surface of the metal. Fluxes act by cleansing the metallic surfaces they are suitably applied to, by preventing formation of oxides, and by assisting the flow and combination of the molten metals in soldering, or welding, or alloying. Spirits of salts, muriatic acid, or hydrochloric acid are suitable fluxes for soft soldering. They require to be prepared specially by dissolving in them clean clippings of zinc, which at once cause an evolution of gas, accompanied by ebullition ; when this action ceases, the flux is ready for use as muriate or chloride of zinc, technically known as killed spirit. This flux must be carefully wiped away after soldering any metal liable to rust. In soldering zinc the surface of the zinc must be clean and bright, when killed spirits are used; crude spirits of salts may be used for zinc which is dull, as it cleans the surface, and in doing so becomes chloride of zinc. Resin or chloride of zinc are used as fluxes in soldering tinned iron. Resin, plain or mixed with oil, may be used as a flux for soft soldering bright clean surfaces, but it leaves a sticky residuum, which, however, does not cause rust. It is used for soldering lead and tin pipes. Tallow, or touch, as it is technically called, is used by plumbers as the best flux for lead soldering; it preserves the bright shaved lead from the tarnish or oxide which would form at once unless touch was applied to the surface. Gallipoli oil is the usual flux for pewter soldering. Borax or sal-ammoniac is used as the flux for hard soldering, and for iron and steel welding. Sal-ammoniac or chloride of zinc for soldering copper and brass.
Key Takeaways
- Fine solder fuses at 370° F.
- Smudge must be carefully prepared to ensure a clean finish.
- Fluxes are crucial for preventing oxidation and ensuring proper flow of metals during soldering.
Practical Tips
- Use fine solder for critical joints where strength is paramount.
- Always test your smudge before applying it to avoid unsightly results.
- Keep fluxes away from surfaces that can be damaged by their sticky residue.
Warnings & Risks
- Avoid overheating the smudge pot, as this can ruin the quality of the smudge.
- Be cautious when using zinc in soldering, as it can make the solder too brittle.
- Do not use fluxes on surfaces that are prone to rust, as they may leave a sticky residue.
Modern Application
While many of these techniques have evolved with modern materials and tools, understanding historical methods like soldering and smudge preparation is crucial for survivalists. These skills can be adapted using contemporary equivalents, ensuring reliable repairs in emergency situations.
Frequently Asked Questions
Q: How do you test the quality of fine solder?
Fine solder can be tested by pouring it out in flat strips and bending it close to the ear; it should emit a very slight creaking sound. If the creaking is too marked, the solder is too fine.
Q: What materials are used for making smudge?
Smudge is made by mixing one part by weight of chalk and two parts of lampblack, grinding them well together with a pestle in a small cast-iron mortar or on a slab with a palette knife, then adding a little melted size to form a paste.
Q: What are the key steps in preparing smudge?
First, mix chalk and lampblack into a paste. Then, half-fill a smudge pot with equal parts of melted size and water, pour in the paste, stir carefully, and warm up the mixture to just below 212° F.