Blow Glass
Glassblowing is the art of creating glass sculptures by manipulating molten glass. Glassblowing was first developed in the Middle East around 300 BC. Since then, glass-blown products have become indispensable to daily life, as well as to scientific innovation, and glassblowing has emerged as a major art form. There are two types of glassblowing: lampworking, which is done with an oxy-fuel torch, and off-hand, which works glass on the end of a hollow tube.
Contents
Steps
Blowing Glass Off-Hand
- Gather the molten glass. With a hollow steel tube, or blowpipe, gather the glass from the furnace (the oven where molten glass is kept). The molten glass in the furnace should be about {{safesubst:#invoke:convert|convert}}.
- A simple but accurate analogy is turning caramel onto an apple. Think of your steel rod as the apple and the furnace as the pot of caramel. Just as you slowly rotate the apple in the hot caramel, gathering glass requires continuous rotation of your steel rod in the furnace, in order to gather the glass steadily and evenly.
- Marver (shape) your glass. Once the glass is stable, carry it to a steel table, called a marver, and begin shaping it. Glass shaping begins with rolling the hot glass on a marver. It is important to make sure that your cylinder is symmetrical. Once you’ve achieved your cylinder, continue to rotate the blowpipe, to prevent the glass from dripping off.
- The marver will suck a lot of heat from the molten glass because the surfaces of the two materials actually touch as the glass rolls across the marver.
- If the sides of the glass get too thin, chill them by rolling them on the marver.
- If the bottom of the glass gets too thick, introduce the glass back into the glory hole (the oven that reheats the glass to keep it malleable) and concentrate the heat on the bottom of the glass. Turn constantly as you heat the glass.
- Cap. Blow into the pipe then cover the hole with your thumb. The positive pressure will cause the trapped air to expand inside the pipe, which in turn will create a bubble. This first gather and bubble is called the parison.
- Once you have an even-walled bubble, you may again marver and gather more glass. Remember to rotate the rod continuously as you move from the marver to the furnace and glory hole.
- Gather again. Collect more glass around your bubble. The number of gathers you make depends upon how big you would like your piece to be — bigger pieces require more gathers.
- If you wanted a bit of color, now might be a good time to introduce it onto your cooler post.
- Shape your piece into a bullet. When you are done with your gathers, use a soaked newspaper and with it shape your parison into a bullet. Then reheat it in the glory hole. Remember to keep the rod rotating at all times!
- Define your shape. Shape your piece by rolling it on the marver, while an assistant blows air through the pipe and into the glass.
- If you want the bubble to move down the glass, marver the sides and not the bottom. With the sides cooler, the bubble will push the bottom down even further when you blow on it.
- If you want the bubble to move out the glass so that the sides expand, marver the bottom and not the sides. With the bottom cooler, the bubble will push the sides out even further when you blow on it.
- Cut in a Jack line. Once your piece is shaped you cut in, or create score lines in the piece’s neck with large tongs known as jacks. The neck should be equal to or less than the diameter of your blow-pipe. Keep rotating your pipe!
- Open the glass and finish the piece. This requires you to transfer your piece to another rod called a punty. It’s one of the trickier parts of glass blowing. A little trade secret, however makes it a whole lot easier. Find a small tool (a file is best) and dip it in water. Carefully etch a line around the neck. This weakens the glass and makes it brittle. It then easily separates from the original pipe.
- Cool your pipe. Place your thumb over the hole though which you were blowing and then carefully dip the pipe into a bucket of water, all the while keeping your thumb over the blow hole to stop the water from shooting up the pipe and ruining it.
- Trim the lip. Reheat the glass in the glory hole and trim the lip with shears.
- Crack your piece off of the pipe. Using a wooden block, tap the pipe forcefully, your piece should drop off the end of the pipe.
- Anneal in order to cool off. Carefully carry it over to the annealer (an oven that cools glass at a controlled rate) and leave it to cool overnight.
Lampworking
- Use lampworking for smaller glass objects. Lampworking is the process of manipulating molten glass over a small torch. Lampworking is used to create beads, for example, or other smaller objects, like paperweights. This section will focus on how to lampwork a small bead.
- Turn on your torch. You could use an oxygen and propane fed torch if you have access to one.
- Heat the mandrel up in the blow torch slow. Try to get a stainless steel mandrel with a ceramic coating. The ceramic coating will keep the molten glass from sticking to the mandrel when you want to take it off.
- Flash the glass through the tip of flame to prime it. If you don't flash the glass, it could go into shock and shatter instead of becoming molten. Flash for about 30 seconds.
- Start bringing the glass closer to the heart of the flame. Hold it in the flame until a nice orange ball develops.
- Keep rotating your glass so that it maintains its round shape.
- Attach the molten tip of the glass to the mandrel.
- Place the glass onto the mandrel and begin wrapping the mandrel away from your body. Wrap until you have full coverage on your mandrel.
- Use the torch flame to sever the glass rod from the mandrel. It's easiest to cut the glass away from its source when both it and the mandrel are in the flame.
- Introduce the mandrel with the glass bead back into the flame, rotating to keep the glass from slipping down.
- If desired, add another color to the existing bead. Do this by following Steps #4 through #7, all while rotating the mandrel and occasionally dipping it back into the flame. This is not for beginners, as it requires dexterity and use of both hands simultaneously.
- Take the mandrel out of the flame and shape, as necessary, with a graphite paddle. Use the paddle to:
- Create better edges
- Create square shapes
- Help even out the contours of a curve.
- Allow the mandrel to cool off a bit before taking it to the annealer, rotating all the while.
Tips
- Glassblowing is an interactive process; the steps vary greatly from form to form. The steps shown above represent general glassblowing techniques. Look for online demonstrations of the different ways to blow glass and the many shapes and styles you can create. Check out these online demonstrations for a great example of glassblowing.
- You can create colored glass by rolling your glass-gather in colored powder. You may also preheat small pieces of colored glass and attach them to a hot blowpipe.
- Wet your hand before gathering glass. This will reduce discomfort from the hot kiln and prevent burns.
- Remember to flash the entire piece in the kiln or glory hole while you are working on it; this prevents cracks.
- Likewise, have a partner help transfer glass from the blowpipe to the punty (rod) to prevent cracks and breaks.
- Make sure your glass gather is as symmetric and level as possible.
Warnings
- Glassblowing is very hot, as in 2000-plus degrees hot! Use extreme caution. Do not try this at home. Do find an instructor, especially if you are just beginning.
- Never lift the glass end of a pipe past eye level after gathering; molten glass may drip onto your hands, face, and in your eyes.
Things You'll Need
- Plenty of time and money
- Glass - Batch or Cullet (scraps of broken or waste glass) to melt down and colored glass
- A partner to assist you
- A Furnace - to melt the glass
- A Glory Hole - to reheat the glass, so that is malleable enough to work with
- A Blowpipe and Punty - to gather and shape the glass
- A Blow torch – if you are lampworking (not discussed in this article)
- A Marver – the steel table upon which you shape the glass
- Hand tools - jacks, wooden blocks, molds, shears to etch and carve the glass
- An Annealer - to cool the glass
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