Glass beadmaking
From Wikipedia, the free encyclopedia
Beads are amongst the oldest human art and technology, dating back 30,000 years (Dubin, 1987). Glass beads have been dated back to at least Roman times. Perhaps the earliest glass-like beads were Egyptian faience beads, a form of clay bead with a self-forming vitreous coating.
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[edit] Common Types of Glass Beads
Glass beads are usually categorized by the method used to manipulate the glass. Most beads fall into three main categories: wound beads, drawn beads, and molded beads. There are composites, such as millefiori beads, where cross-sections of a drawn glass cane are applied to a wound glass core. A very minor industry in blown glass beads also existed in 19th century Venice and France.
[edit] Wound Glass Beads
Probably the earliest beads of true glass were made by the winding method. Glass at a temperature high enough to make it workable , or "ductile", is laid down or wound around a steel wire or mandrel coated in a clay slip called "bead release." The wound bead while still hot may be further shaped by manipulating with graphite, wood, stainless steel or marble tools and paddles, this process is called marvering, originating from the French word "Marver" which translates to "Marble". It can also be pressed into a mold in its molten state. While still hot, or after re-heating, the surface of the bead may be decorated with fine rods called stringers of colored glass. These are called lampwork beads.
[edit] Drawn Glass Beads
The drawing of glass is also very ancient. Evidence of large-scale drawn-glass beadmaking has been found by archeologists in India, at sites like Arekamedu dating to the 2nd century CE. The small drawn beads made by that industry have been called Indo-Pacific beads,(see [1]) because they may have been the single most widely traded item in history--found from the islands of the Pacific to Great Zimbabwe in southern Africa.
There are several methods for making drawn beads, but they all involve pulling a strand out of a gather of glass in such a way as to incorporate a bubble in the center of the stand to serve as the hole in the bead. In Arekamedu this was accomplished by inserting a hollow metal tube into the ball of hot glass and pulling the glass strand out around it, to form a continuous glass tube. In the Venetian bead industry, molten glass was gathered on the end of a tool called a puntile ("puntying up"), a bubble was incorporated into the center of a gather of molten glass, and a second puntile was attached before stretching the gather with its internal bubble into a long cane. The pulling was a skilled process, and canes were reportedly drawn to lengths up to 200 feet long. The drawn tube was then chopped, producing individual drawn beads from its slices. The resulting beads were cooked or rolled in hot sand to round the edges without melting the holes closed; were sieved into sizes; and, usually, strung onto hanks for sale.
A modern example of mechanically-drawn glass beads is the micro-bead or "seed bead", so called for its tiny, regular size. Seed beads are the most common type of modern glass bead. The seed bead is a small bead typically less than 6 mm, traditionally monochrome, and manufactured in very large quantities. Modern seed beads are extruded by machine and some, (Miyuki delicas) look like little tubes.
[edit] Molded Beads
Increasing in labor costs are pressed or molded beads. These were (and are) made in the Czech republic, in what was once called Bohemia. Thick rods (20cm?) are heated to molten and fed into a rube goldbergian contraption that stamps the glass, including a needle that pierces a hole. The beads again are rolled in hot sand to remove flashing and soften seam lines. By making canes (the glass rods fed into the machine) striped or otherwise patterned, the resulting beads can be more elaborately colored than seed beads. One `feed' of a hot rod might result in 10--20 beads, and a single operator can make thousands in a day.
The Bohemian glass industry was known for its ability to copy more expensive beads, and produced molded glass "lion's teeth", "coral", and "shells", which were popular in the 19th and early 20th century Africa trade.
[edit] Lampwork Beads
A variant of the wound glass beadmaking technique, and a labor intensive one, is what is traditionally called lampworking. In the Venetian industry, where very large quantities of beads were produced in the 19th century for the African trade, the core of a decorated bead was produced from molten glass at furnace temperatures, a large-scale industrial process dominated by men. The delicate multicolored decoration was then added by people, mostly women, working at home using used an oil lamp or spirit lamp to re-heat the cores and the fine wisps of colored glass used to decorate them. These workers were paid on a piecework basis for the resulting lampwork beads. Modern lampwork beads are made by using a gas torch to heat a rod of glass and spinning the resulting thread around a metal rod covered in bead release. When the base bead has been formed, other colors of glass can be added to the surface to create many designs. After this initial stage of the beadmaking process, the bead can be further fired in a kiln to make it more durable.
Modern beadmakers use single or duel fuel torches, so `flameworked' is replacing the older term. Unlike a metalworking torch, or burner as some people in the trade prefer to call them, a flameworking torch is usually "surface mix"; that is, the oxygen and fuel (typically propane, though natural gas is also common) is mixed after it comes out of the torch, resulting in a quieter tool and less dirty flame. Also unlike metalworking, the torch is fixed, and the bead and glass move in the flame. American torches are usually mounted at about a 45 degree angle, a result of scientific glassblowing heritage; Japanese torches are recessed, and have flames coming straight up, like a large bunsen burner; Czech production torches tend to be positioned nearly horizontally.
[edit] Dichroic Glass beads
Increasingly, dichroic glass is being used to produce high-end art beads. Dichroic glass has a thin film of metal fused to the surface of the glass, resulting in a surface that has a metallic sheen that changes between two colors when viewed at different angles. Beads can be pressed, or made with traditional lampworking techniques.
[edit] Furnace Glass
Italian glass blowing techniques such as latticinio and zanfirico are adapted here to make beads. Furnace glass uses large decorated canes built up out of smaller canes, encased in clear glass and then extruded to form the beads with liner and twisting stripe patterns. No air is blown into the glass. These beads require a large scale glass furnace and annealing kiln for manufacture.
[edit] Lead crystal
Lead crystal beads are machine cut and polished. Their high lead content makes them sparkle more than other glass, but also makes them inherently fragile.
[edit] Types of glass used in Lampwork beads
[edit] Rod versus Sheet
Most lampworkers use rods of glass 7--8 mm in diameter, though premade stringers come in 1, 2 and 3 mm sizes (depending on the brand), and some brands come in very thick diameters (15mm or more.) Sheet glass can be cut with tools into strips, though they're easier to manipulate if attached to a rod first. (Glass also comes in particles of various sizes(frit or powder), but these are typically surface decorations in lampworked beads.) Many manufacturers who once only sold their glass in sheet or very thick rod now provide rods for lampworking use.
Window glass can actually be used, but usually isn't, because it's not formulated for flameworking (it's shocky, that is, cracks and shatters in the flame) and there is little in the way of color available.
[edit] Soda lime
The most popular lampworking glass comes from Italy and is currently made by the Effetre company. Before it was sold, it was called Moretti, and some people still call it that. Confusing matters is that a cousin started a rival company; their product is called Vetrofond, and is very similar. Effetre is a soda-lime glass, and, again is the type most commonly used by lampworkers. Perhaps the second most popular soda-lime glass (in the USA) is made by Bullseye, which markets their product as being particularly compatible (find/link/write article about glass coe/compatibility). Spectrum, Uroboros make 96coe glasses. Japanese Satake, German Lauscha, Czech (Ornela) and even Indian (PIG) soda lime glasses are also known. New firms seem to be springing up like weeds to serve the glass beadmaking market, which in the USA has grown from "about 30" to 70,000 people (Kate Drew Wilkerson, interview, Dale Smeltzer's internet-only glass talk radio)
[edit] Lead
In addition to soda lime glass, lampworkers can use lead glass. Lead glasses are distinguished by their lower viscosity, heavier weight, and somewhat greater tolerance for coe mismatches. Satake, Czech and German glasses (the latter being marketed primarily to glassblowers) all come in lead versions. New to the market is also Gaffer Glass, its 96 coe and is made in New Zealand.
[edit] Borosilicate
Finally, beadmakers can and do use borosilicate glass, a very hard glass requiring greater heat. This is laboratory glass, such as Pyrex. Sue Ellen Fowler is credited for developing many of the original recipes for colored borosilicate glasses, which became the basis for the Northstar company's first products. Donald Schneider (personal conversation, late 1990s) recalls how years ago he had to make all of his own borosilicate colors (he still makes a tin white.) Northstar, and new Glass Alchemy (started by a former chemist at Northstar) now offer many colors, introducing several new ones every year. At one time, soft (soda lime and lead) and hard (boro) glasses had distinctly different looking palettes, but demand on the part of soft-glass artists for the silver strike colors on the one hand, and the development of the bright, cadmium based `crayon colors' in the boro line on the other, has softened the distinctions between them considerably.
[edit] Basic Technique for Lampworking
[edit] Preparing the mandrel
In any case, the beadmaker starts by dipping a mandrel, or wire (stainless steel welding wire, cut into 9 or 12inch lengths is typical, at least in the USA) into a clay based substance similar to kiln wash and letting it dry. Some brands allow for drying in the flame.
[edit] Heating rod and mandrel
The flameworker then selects rods of glass which they heat in the flame of her torch. The mandrel must also be heated, or the glass will not stick. When both glass and mandrel are sufficiently warm, the beadmaker starts rotating the mandrel (usually with the non-dominant hand) while allowing the glass to wind upon it---sort of like pulling out a strand of cotton candy, or wool batt while spinning.
[edit] Beginner Bead
The usual beginner bead is a simple donut shape. The beadmaker can use a paddle, a small slab of graphite or brass to shape the glass in different ways---long thin barrels, bicones, tabs, and so on. Czech beadmakers, who can produce up to 1200 (identical) lampwound beads in 2--3 days, are particularly known for their use of jigs to help rapidly shape the bead into the desired silhouette.
[edit] Shaping the Bead
Getting a good shape is quite often the longest part of the process, though onlookers tend to be most impressed with surface decoration. Some beadmakers rely solely upon heat and gravity to shape their beads; most at least use a graphite paddle to coax the bead into the shape they want. Other common tools for shaping beads are mashers, tweezers, picks, and even the rod of glass itself.
[edit] Decorating the Bead
There are many ways to decorate a bead. One is to draw with a stringer, or fiber (a small thread, usually 3 mm or less in diameter) of glass on the surface, making dots, lines, or combinations. Dots are particularly versatile and can be piled on top of each other in many intriguing ways. Additionally, a sharp pointed object---for example, a tungsten rake (or pick) or stringer of glass can be dragged through the surface design to make feathers, hearts or other designs. Another very old, traditional design involves sagging one part of a striped bead by heating it more, or rubbing it with the paddle to shift the design into waves.
Glass can also be broken into very small chunks (frit) or even finely ground powders (e.g. Thomspson enamels) in which the bead can be rolled; it can also be decorated with metals---silver, gold, copper, palladium, and platinum. These are typically applied as very fine leaf, slightly thicker foil, as fine wire, as fine mesh, or even as a metallic deposit (fuming.)
[edit] Annealing
Good quality glass beads, like any warm or hot-glass item, are then annealed. Large or complex beads go into an annealing kiln immediately; smaller ones may be allowed to cool slowly, as with a fiber blanket or by being plunged into vermiculite, and then "batch annealed" at a later time.
[edit] Other methods for making glass beads
Lead glass (for neon signs) and, especially borosilicate is available in tubing, making true blown beads possible. (Soda lime glass can be blown at the end of a metal tube, or, more commonly wound on the mandrel to make a hollow bead, but the former is unusual and the latter not a true mouth-blown technique.) In addition, beads can be fused from sheet glass or using ground glass.
Modern Ghana has a lively industry in beads molded from powdered glass. Also in Africa, the famed Kiffa beads are made in Mauretania, historically by women, using powdered glass that the beadmaker usually grinds herself from commercially available glass seed beads and recycled glass.
Molded ground glass, if painted into the mold, is called pate de verre, and the technique can be used to make beads, though pendants and cabochons are more typical. Lampwork (and other) beads can be painted with glass paints.
[edit] Additional Techniques for Lampworked beads
Beads can be sandblasted; they can be faceted, using lapidary techniques. "Furnace glass" beads, more elaborate versions of the old seed bead technique described above, are also being made. Chevron beads are multi-layer beads once exclusively made using hot-shop techniques to produce the original tubing; but now some lampworkers make similar designs on their torches (using borosilicate,--Kevin O'Grady, demonstration, 2004 Gathering) before lapping the ends to reveal the various layered colors. It should be noted that as torches get bigger and more powerful, the cross-over between lampworking and furnace glass continues to increase.
[edit] Brief history of modern beadmaking
Lampworked beads (with the exception of Asian and African beadmaking) have pretty much strictly been the provenance of Italian, and, later, Bohemian lampworkers for the last four hundred years or so who kept the techniques secret. Thirty or so years ago, some American artists started experimenting with the form. Their early efforts, by today's standards, were crude-not surprising when there was almost no documentation, and none of the modern tools. However, they shared their information, and some of them started small businesses developing tools, torches and other equipment. The "stump shaper" a popular shaped paddle, is named after Loren Stump, for example.
This group eventually formed basis for the Society of Glass Beadmakers, which recently changed its name to the International Society of Glass Beadmakers. Techniques diffused through the population, via early books such as Cindy Jenkins' You can make Glass Beads; the ISGB's annual conference and their online forum; and just generally the philosophy of sharing ideas, tips and techniques. This philosophy continues to permeate the glass beadmaking world today, resulting in a huge diversity of approaches, styles and beads.
