Laboratory Glass-Working for Scientists - Sciencemadness Dot Org

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GLASS-WORKING EQUIPMENT These needles have the disadvantage that, owing to their fineness, they tend to oxidize away readily and may also be melted if held in a hot flame for any appreciable length of time. Forceps will be found useful in many circumstances. These are usually made of steel and should be designed so that there is no tendency for the soft glass to slip out easily. This will be avoided if the points are bent inwards so that they meet at an angle of about 25°. The forceps should either be long enough not to get too hot in use (about 10 inches long) or else they should be insulated in some way. Flask clamps are made to fit a wide range of sizes of flask. These are devices for holding flasks while the necks are being worked and enable the whole flask to be rotated easily. They usually consist of a handle with three or four sprung prongs which hold the body of the flask. Some clamps are made so that they can be adjusted to fit a range of flask sizes. Many operations require only a very modest set of tools, and too great a stress can be laid on the variety of tools required for any operation. As an example, forceps are useful for drawing off small pieces of glass or for pulling out excessively thick parts of the wall of a joint, but both these operations can be carried out by fusing a length of glass rod to the part to be drawn off and using this as a handle for the drawing operation. As in many other fields of craftsmanship, a skilful operator can work wonders with inadequate and makeshift tools, but his job would be much easier if he had all the equipment he needed, although for much of the time he may only use a very few of the tools at his disposal. There are times when the less commonly used tools will be useful, but on the other hand the glassworker should not allow himself to be deterred by the fact that he does not have a vast array of tools. I. C. P. SMITH (1947b) has reviewed some uses of tools in lampworking. Wax for Tools Tools can be used without lubrication, but care is necessary in this case to prevent the tool oxidizing and the oxide entering the glass, which is then liable to crack on cooling. A lubricated tool slides more easily over the hot glass. Beeswax and paraffin wax have been used as lubricants; a thin film only is used. A better lubricant, advised by I. C. P. Smith (1947b), is paraffin wax mixed with some colloidal graphite. The colloidal graphite is not rapidly burnt off the tool, and it retains its lubricating properties up to 600 Q C. An over-heated tool can also be dipped into distilled water (5 oz) containing colloidal graphite (| oz of Aquadag). The tool picks up a layer of graphite. 32
WAX FOR TOOLS When soft asbestos is used on the bench, waxed tools are likely to pick up shreds of asbestos which can cause trouble. It is best to avoid soft asbestos in this case. When constructing high vacuum apparatus, waxed tools should only be used when the apparatus under construction can be thoroughly cleaned afterwards. Otherwise wax may be present in the vacuum system, and will be removed by pumping only with extreme slowness. Carbon Plates Carbons A few thin, rectangular plates of carbon can be very useful on the glass-working bench. The faces of these plates are of use in flattening the ends of tubing, in blowing flat-bottomed bulbs, and in shaping \J FIGURE 5. A carbon plate and a carbon rod. Both are attached to a handle pieces of molten glass as, for example, in making the paddle for a glass stirrer. For shaping purposes it is sometimes preferable to have a handle attached (FIGURE 5). Plates ranging from i to f inch in thickness and of the order 3 by 6 inches are convenient sizes. Carbon Rods Carbon rods with one end filed to a conical shape make very good 33
Page 1 and 2: FOREWORD ACKNOWLEDGEM ENTS PREFACE
Page 3 and 4: CONTENTS Grinding glass Releasing f
Page 5: ACKNOWLEDGEMENTS We thank the follo
Page 8 and 9: PREFACE scattered in the literature
Page 10 and 11: INTRODUCTION ready outgassing on ba
Page 12 and 13: INTRODUCTION in succession broke th
Page 14 and 15: INTRODUCTION MOREY, G. W., 1938, Th
Page 16 and 17: PHYSICAL AND CHEMICAL PROPERTIES OF
Page 30 and 31: Pyrex PHYSICAL AND CHEMICAL PROPERT
Page 36 and 37: GLASS-WORKING EQUIPMENT 3 The Glass
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BASIC GLASS-WORKING OPERATIONS meta
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BASIC GLASS-WORKING OPERATIONS but
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BASIC GLASS-WORKING OPERATIONS with
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BASIC GLASS-WORKING OPERATIONS to t
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Chapter 5 THE MANIPULATION OF LARG
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THE MANIPULATION OF LARGE TUBING th
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THE MANIPULATION OF LARGE TUBING ro
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THE MANIPULATION OF LARGE TUBING jo
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SOME OPERATIONS WITH A GLASS-WORKIN
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SOME OPERATIONS WITH A GLASS-WORKIN
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Chapter 7 METAL-TO-GLASS SEALS ALTH
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METAL-TO-GLASS SEALS The finished b
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METAL-TO-GLASS SEALS Multiple Wire
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METAL-TO-GLASS SEALS will not be le
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METAL-TO-GLASS SEALS but in either
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METAL-TO-GLASS SEALS 29 per cent Ni
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METAL-TO-GLASS SEALS hard glasses i
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METAL-TO-GLASS SEALS Glass tubing m
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SOME TYPICAL SINGLE PIECES OF EQUIP
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Chapter 9 THE ASSEMBLY OF COMPLEX A
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THE ASSEMBLY OF COMPLEX APPARATUS d
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THE ASSEMBLY OF COMPLEX APPARATUS d
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THE ASSEMBLY OF COMPLEX APPARATUS u
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THE MANIPULATION OF SILICA with a f
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THE MANIPULATION OF SILICA surface
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Anhorn, V. J., 5, 28, 41, 47, 123,
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Abrasives, 39 Alkaline attack on gl
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Lead glass, 23,108 Lead glass compo
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