CHAPTER IV 
soldering (continued) 
Gas—Jeweller's jet—Blowpipes—Bellows—Management of blowpipe flame—Spirit lamp—Blowlamps—Cokefire—Charcoal fire—Furnace. 

Coal-gas is the simplest and most generally available fuel for the purpose of soldering. It is employed in a rather different manner for small and for large work. For jewellery and other small articles a jeweller's jet and a mouth blow pipe are the tools used. While for large work a blowpipe, Fig. 9, and bellows, Fig. 10, are necessary. The jeweller's jet, Fig. 12,is a small iron stand through which the gas-pipe passes to a horizontal tube, 4 or 5 inches long, pivoted at one end above it. The horizontal tube can be swung right round the pivot, and the gas supply is so arranged that when the tube, or jet, is in the position for soldering a full supply of gas can pass through it, while, as it is turned round out of the way, the supply is automatically cut down until only sufficient remains to keep the jet alight. The end of the tube is cut off at an angle of about 45°. The iron stand is generally fixed to the bench on the right-hand side of the worker. The mouth blowpipe, Fig. 11, used in conjunction with this jet, is a tapering tube of brass about 8 inches long, the smaller end being bent round at right angles. The tube varies in diameter from about \ inch down to an opening large enough to just admit an ordinary pin. A second blow pipewith an openingabout twicethis sizeisusefulforrather larger work. For large work, however, the blowpipe and bellows must be used. The blowpipe in this case consists of two concentric tubes, measuring perhaps 3/8 and 1/8 inch in diameter respectively. They are bent round to nearly right angles at one end, like the mouth blowpipe.. The outer tube is for gas, the inner for the compressed air from the bellows, the supply of both being regulated by a tap. In choosing a blowpipe see that you get one with plenty of room through the taps. You should have a bore of § inch all the way from the main to the mouth of the blowpipe, which, however, may be a little smaller. The bellows most generally used are those known as Fletcher's No. 5. They are worked by the foot. On the underside of the bellows is an india-rubber disc, or rather two discs, covered by a net which prevents them from expanding too far. Theirpurpose is to make the blast continuous, for one which came in puffs would not be always satisfactory. These rubber discs sometimes burst, and it is well to know how to replace them. It will be found that the net is held on by a wire running round its circumference. Untwist the join and the net will come off. The two rubber discs are fastened on with a twisted wire in the same way. Remove them and see that the valve underneath is working well. Put on the new discs and be careful in fixing the wire that you smooth out every pleat round the edge of the rubber. Remember to bend the ends of the wires out of reach of the discs when they are expanded. You don't want to puncture them. Replace the net as before. 

We come now to the management of the blowpipe flame. Let us take the jeweller's jet first. If you light the jet and turn it round till full on you will have a loose, flickering flame about a foot long, blue at the bottom and white nearly every where else. Turn it down till the flame is about 6 inches high. Now take the mouth blowpipe in your hand. The larger end is tinned, to be clean for the mouth. Keep the cheeks inflated and try to blow a gentle, continuous stream of air through the pipe. With a little practice the blast need not stop even while you take a fresh breath into your lungs through the nose. Do not blow too hard; quite a gentle blast is required, just as though you were whistling to your self. When you have had a little practice with the blowpipe move its small end to a position immediately over the 
horizontal tube of the jet, and about § inch from the end where the flame is. Turn the blowpipe to such an angle that the flame is blown downwards to the left at about an angle of 45°. The character of the flame will be quite changed. Instead of being nearly white it will be blue, with some flashes of white towards the point. The jet of air has both altered the direction of the gas-flame and made it hotter, for it is now burning a good dealmore oxygen from the air. This is the cause of its change of colour. If you blow hard you will have a roaring, rough-edged, very hot flame, useful for heating a largish piece of work, but rather likely to melt any thin or projecting parts of it. If, however, you breathe gently through the pipe you will have a silent flame, with less ragged edges. This flame is not so fierce as the other, but it is hot enough to heat the work up suffici ently, and to melt the solder. Now turn the jet round till you have a flame only 4 inches high. Move the point of the blowpipe till it is only J or J inch from the end of the horizontal tube. (It is cut off at an angle of 45°, but these measurements are taken from the top of the slope.) The character of the flame is changed again. You have a sharp spike of flame 3 or 4 inches long. And, if you look, you will notice that it consists of an outer, dark blue flame, with an inner, light blue one, extending about half the way along. Take the wig, Fig. 34, in your left hand and hold it beyond the end of the flame. Gradually bring it nearer. The fine iron wires of Avhich it is composed will quickly become red, then white hot, and then burn—throwing out bright sparks in all directions. Move the wig away, and try again and again to see which part of the flame will make the wires begin to burn most quickly. You will find that the hottest part of the flame lies just beyond the tip of the inner, light blue cone. You have now learnt what you can do. You can heat the whole work up with the soft, gentle flame, and you can then, by shifting the position of the blowpipe, direct a sharp, very hot flame on to the solder and the parts near it. This is just what you should do in soldering, if you have sufficiently warmed the whole work with the gentler flame, then immediately the hot, pointed flame touches the solder it will melt and run into the joint. With the large blowpipe and bellows you may get a similar variety of flames: the roaring,raggedflame forheatingupandsolderinglargework; the quieter, gentler flame for smaller, more delicate work, parts of which might become melted in a fiercer flame; and the sharp, intensely hot flame which is so useful in actually melting the solder when the work has been sufficiently heated. You must practise with these different flames, so that you may produce each of them at will, and keep them entirelyundercontrol. Eachtypeofflamemaybeproduced however high or low the gas may be turned. 

It is a good plan when annealing or soldering to move the work every now and then out of range of the flame, even for a fraction of a second. You can then see at once how it is getting on—if any part has become red-hot, or is in danger of becoming melted. When using the large blow-pipe, of course you move that instead of the work. If you have a difficulty in getting the work hot enough, probably more gas is required. But do not use a bigger flame than is necessary. For that is both wasteful and dangerous. You will find that the work will get hot quicker if you can hold it considerably below the jet and direct the flame nearly squarely on to it: while if the flame makes as it were a glancing blow at the work much of its heat is wasted. You will notice this par ticularly with the large blowpipe when you try to heat some piece of work which is nearly at the limit of the blowpipe's power. Indeed, in such a case it is well to build a temporary wall of coke, charcoal, firebrick, gas-carbon or any other not very fusible material behind the work to catch the flame when it has passed and to turn it back on to the work again. 


It often happens that a room otherwise available for metal-working has no supply of gas. This need not, however, prove an insurmountable obstacle, for soldering lamps, burning spirit or oil may be used instead. Work as large as a fair-sized brooch can be soldered by means of the spirit lamp shown in Fig. 13.  Resting on a cast-iron foot is a large reservoir for methylated spirit. At a little distance is an inclined tube filled with cotton waste or wick, and connected by a tube with the reservoir. The inclined tube should be about| or1inchindiameter. Whenthe wickislightedyou have a very good flame. You can regulate it by pulling the wick up or down the tube. The flame is extinguished by dropping on to it the little disc of metal attached to the hinged curved wire shown above the reservoir. A cap is provided to cover the inclined tube and prevent the escape of the spirit when the lamp is not in use. The lamp is used in conjunction with the mouth blowpipe. 

For larger work a lamp burning paraffin would berequired. The Swedish blowlamps known as yEtnas are most useful. Of similar make are the Barthel brazing lamps, their principle of construction being similar to that of the lamps used by house decorators for burning paint off woodwork. The most useful size to buy holds about a quart of oil, and will burn for an hour with but little attention. It costs about 15s. The construction is shown in the Fig. 14. A is the reservoir, two-thirds full of paraffin oil, which has been poured in at the screw-cap B. C is a little air-tap. D the pump by which air is forced into the reservoir. E is the pipe for the oil, which runs from near the bottom of the reservoir through the tube F, and escapes by a minute hole at G. H is a shallow depression at the top of the reservoir. This little cup is filled with methylated spirit, which, when lighted, heats the tube F so much that any oil within it is turned to vapour. This gas, emerging from the pinhole G, burns with a hot blue flame, and rushes forward, keeping the tube F red-hot on its way. To start the lamp, open the air-valve C, fill the cup H with spirit and light it. When it has nearly all burnt away, but not before, close the tap C and pump some air into the reservoir. This air will, of course, collect at the top of the reservoir, above the oil. The pressurewillforcethe oilto escapebythe onlywaynowopen to it—up the pipe E, through the almost red-hot tube F, where it will be turned to vapour, and out into the air at G, where it catches alight. It is well to pump as much air as possible into the reservoir, as this will send a good supply of oil to the vaporiser F. To extinguish the lamp it is only necessary to open the valve C. This relieves the pressure, and no more oil is forced up the tube E, so the lamp goes out at once. If you begin to pump air into the reservoir before the vaporiser is hot enough, you will drive through the jet G a stream of paraffin instead of gas. The remedy is: Open the valve, then heat the vaporiser more and start afresh. The lamp will burn upside down or in any position. But it sometimes happens, when the oil is nearly used up, that a sudden shake may put the flame out. Dense black fumes of paraffin vapour come from the jet instead. A match held near G may light the lamp again. But if the pressure is too great it may blow the match out instead. Therefore relieve the pressure a little by opening the valve C for a second or two. The jet will light up quite easily then. But at any time you can stop the lamp by opening the valve. So you will have no real difficulty with it. As a rule, as soon as the lamp is fairly alight, pump as hard as you possibly can. The lamp will then go for a quarter of an hour or more without any further attention. The flame from an iEtna lamp, quart size, is about 9 inches long, blue in colour and it roars considerably. When you have finished with the lamp always leave the valve open. If you do not, and the lamp is warm, oil will slowly rise in the tube E and flow out of the jet. Some of this oil will become burnt inside the vaporiser when next the lamp is lighted and clogthe jet. Cleaning needles are provided with the lamps, and they should be used if ever the jet seems to have become at all clogged. Should you run out of methylated spirit, the lamp can be lighted, though it is not a good way, by holding the vaporiser, till hot, between the bars of an ordinary fire. Then close the valve and pump as usual. 

It sometimes happens that a larger piece of work than the lamp can properly heat up, has to be soldered. The simplest way to overcome the difficulty is to make up a good fire in an ordinary firegrate, and wait until it has burnt clear. Then make a hollow place near the centre and place your work in it. The heat of the fire should be sufficient to make the whole work red hot. And, if the flame from the blowlamp be brought to bear on it while yet in the fire, any part may be sufficiently heated to make the solder run. 
The old method of soldering, employed before the intro duction of coal-gas, was that in which a charcoal fire, excited by a blast from one or more pairs of bellows, was used. This was the method invariably employed until the middle of the nineteenth century, and in many places, notably the East, it is used to this day. Much of the most beautiful work in existence was executed by its aid. Charcoal may be purchased almost anywhere, or it can be made in small quantities as follows : Fill an iron box—an iron saucepan, for instance—with small logs of wood. Close it to exclude the air, and fasten the lid on with stout iron wire. But leave an opening for the escape of the gases. If the lid fits loosely it will do. Place the saucepan on a fire and leave it there until no more gas is driven off. Remove it from the fire and leave it till cold, and the charcoal will be found ready for use. Use a cast-iron saucepan, not a soldered one—for the latter would fall to pieces in the process. Then make a sheet-iron tray or hearth measuring about a foot across, with sides two inches high. It is well to make it work on a pivot, for it is a very great convenience to be able to turn work about while soldering. In the centre of the hearth is a small flat box of sheet iron, in the top of which a large number of small holes have been drilled. This box is con nected by a pipe with the bellows. To make the hearth ready for soldering, place a red-hot coal on or near the perforated box, and heap the charcoal over it. Blow with the bellows, gently at first, but harder as the fire spreads, just as you have seen a blacksmith do. When a good fire has been obtained, level a space near the centre, and there place your work,pilingup the hot charcoalall round. Work the bellows till you see the solder flow, then cease blowing and move some of the charcoal away, so that the work may cool down. The old workers used to have, for small work, a thin iron bowl with many holes punched through it from the inside. This bowl they placed over their work, and heaped the charcoal right over both. They would leave one of the punched holes uncovered, so that they could look in from time to time to see how the work was getting on. The holes in the bowl were punched from the inside with a sharp spike. This left ragged edges on the outside of each hole, which kept small pieces of charcoal from falling in. 

A furnace which will require no bellows can be made in the following way. Take some clay and beat it up well with a little sand. With this, or with bricks, build a circular furnace about a foot in diameter inside, with walls four inches thick. Leave a hole four inches square at one side near the ground. Just above this put an iron grating all over the floor of the furnace. The air will then be able to enter at the square hole and pass through the grating. Build the walls straight up for about a foot above the grating. Then arch them over the top, leaving room for a piece of three-inch iron piping for a chimney. This should run into an ordinary house chimney. Leave an opening at one side, six inches square, for a door, and close it with a piece of firebrick. Make two or three peep-holes through the side of the furnace, closing them with pieces of mica. Put a thick layer of charcoal over the grating, and light it by putting some red-hot coals among it. Then close the door. You will get a good draught, and can regulate the heat by varying the size of the opening under the grating. The amount of heat produced varies with the wood from which the charcoal was made. That made from birch is said to give the highest temperature. When the furnace is hot the work to be soldered, resting on a piece of thin sheet iron or a piece of fireclay, is placed on the hot charcoal and the door closed again. It is necessary to watch the work all the while through the mica window. Immediately the solder flows 
open the door. This, by stopping most of the draught throughthe charcoal, willpreventtheheat from risinghigher. Removetheworkat once withapairoflong-handledtongs. A furnace very similar to this was very widely used in olden times, though bellows instead of the long chimney were often employed in conjunction with it. It was also used for enamelling. The grate under the ordinary scullery boiler or copper is arranged in a very similar manner. 

It is well to remember that the fumes given off by hot charcoal are injurious, so they should be led into a chimney or into the open air.