You Can Learn Glass Blowing (Feb, 1938)
You Can Learn Glass Blowing
THE reason that amateur glass blowing is such an interesting hobby is that the work acts as a stimulant to your creative ability. With very simple and inexpensive tools, in a corner of a room or in the attic or basement, you can quickly learn to make dozens of useful and ornamental pieces such as vases, small glasses of different shapes, beverage sippers and other articles of that nature. With further practice and experience you will not find it difficult to make the tiny animal, bird and flower novelties or “whatnots,” which are so popular in the home, and know that the design is original and that a similar article cannot be purchased in the stores.
If you are an amateur chemist, a knowledge of glass blowing will enable you to repair broken retorts and other apparatus, in addition to making test tubes and other small equipment. Or do you prefer to dabble with electricity? Then try blowing glass bulbs for homemade experimental electric lamps, along the line of the mercury-arc type of light, which is similar to the well-known “neon” tubes. Amateur model makers frequently have use for miniature glass parts, and in fact there are very few crafts or hobbies where a knowledge of glass blowing would, not be useful. Locate the glass-blowing laboratory in a convenient corner free of drafts and with poor illumination, so that it will be easier to judge the condition of the heated glass. An ordinary workbench, about 3 feet high, is satisfactory, or use a kitchen table. Cover the top with sheet asbestos, or preferably asbestos board, and at the back provide a rack for holding your stock of glass tubing in various sizes.
All amateur glass blowing, and a considerable amount of professional work, is done with glass tubing instead of using molten glass in a heated retort. You will find that soft sodium glass is most satisfactory; it should have walls at least 1 mm thick, and a bore of from 5 to 10 mm for general work. Quite often you can purchase this at a local drug store or high school laboratory, otherwise you can order it of a scientific supply house. Ordinarily the tubing is offered in 5 or 6-foot lengths and costs as little as 25c a pound, according to the amount purchased.
Professional and advanced work is done with two or more special blowpipes which oppose each other and are fed with both gas and air under pressure. A professional outfit of this kind is shown in one of the illustrations. However, the beginner can handle small work with the aid of a bunsen burner such as those used for chemical experiments. The larger size, like the one shown in use by the author, will afford a much hotter flame and is to be preferred. It is also supplied with extra gas jets of different sizes, which allow some degree of control over the gas-and-air mixture. If the mixture is too rich there is the possibility that the glass will become darkened as it is heated.
If you should wish to construct a professional-type blowpipe at once, you will find that one made entirely of glass gives a very powerful flame. Attach rubber tubes with stop-cocks to control the amount of gas and air. The latter can be supplied by a small foot bellows. Adjust the mixture to give a hot blue flame that ends in a fine point.
Rotation: In order to heat the tubing evenly it is necessary to keep it revolving in the flame, generally by turning it with the left hand. In case the middle of the tube is being heated, use both hands. This must be done carefully and in synchronization so that the glass does not become twisted.
Ordinarily the professional glass blower heats each end of the tube and draws it off into a narrower tubing, which is broken off to leave a smaller 6-inch spindle at each end. The spindle is much easier to turn than the larger tubing. A more satisfactory method for the beginner is to secure a number of corks in different sizes and drill them to take short pieces of small tubing. These can be inserted in either end of the working tube and serve as removable spindles. Glass is not a good conductor of heat, so the corks will not become charred.
“Gathering” Glass: This is a most important operation for the beginner to learn. Possibly you have tried your hand at glass blowing in the past and have given it up because on blowing the heated tubing it quickly expanded into a bulb with walls so thin that they immediately collapsed. This is avoided by gathering the glass so as to thicken the walls of the tubing. As an experiment, heat the middle of a short piece of glass, and while rotating it uniformly, gradually and carefully bring the hands together. This must be done slowly and with judgment. You will find that the walls of the heated part of the tubing will become thicker and, if you wish, the bore can be entirely closed. Cork the end of one spindle and blow gently into the other, meanwhile continuing the rotation. The heated glass will expand into a more or less perfect bulb, according to the amount of skill you have acquired, and the walls will be thick enough for practical use.
In this connection, the blowing of different sizes and shapes of bulbs in a single piece of tubing is excellent practice and will provide skill in handling glass.
Making a Beverage Sip per: A glass “straw” for sipping cool drinks is an easy project to commence with, and theymake very attractive and useful bridge prizes. Choose a piece of narrow tubing and heat one end until a considerable amount of glass has been gathered. Blow into it very gently to form a thick-walled bulb about 3/4-inch in diameter, then while the glass is still hot, almost flatten it with a tweezer-like tool made by bending in half a narrow piece of spring brass. Suction applied to the open end of the tube will make the sides of the flattened bulb concave. Heat and bend it at an angle to the stem, then heat a small spot, blow haard into the tubing and a hole will be formed. This can be made smooth by further heating. Make the stem to the desired length by cutting it with a triangular file and then tapping, when it will part neatly. Heat the mouth of the stem to smooth and round it. The stem can be heated and bent in the middle if desired.
Flower Vase: Cut a 12-inch piece of your largest tubing and at 3 inches from one end gather the glass together, closing the bore, to form the stem. Gather more glass immediately next to the stem, then gently blow it out into a small bulb. Before the glass has cooled, bring the hands to gether so as to “squeeze” the bulb to shape. Blow six more bulbs, closely adjoining, in the same manner. The ends are flared, to form a base and mouth respectively, by rotating the heated glass against a spear-shaped tool made of sheet steel or heavy brass. Lips are formed around the mouth with a sharp corner of a putty knife ground to a triangular shape.
A distinguishing feature of handmade work is that it is seldom uniform, otherwise it would be in the same class as machine-blown glassware. For this reason it is not necessary, or advisable, to try to make the vase absolutely perfect.