summer we were privileged to have Hugh Randall as an intern in our studio.
Hugh is a local high school student who approached our studio eager
and excited to spend some time learning about the history of glass and
how it is used today as an art form. After hours of research and hands
on application, he presented and allowed us to share his paper through
our website. Read on and enjoy learning about the history of glassmaking
tools and how they are used today. Thanks Hugh & good luck!
A trade kept alive
By Hugh Randall
Making and working glass has been
one of the greatest advancements in technology up to the modern age;
and has greatly influenced our way of living. When glassmaking was first
invented in Mesopotamia around 3,000 BC, people were using primitive
methods to make glass pieces. The Mesopotamians had discovered a material
that would provide new art, style, and better ways of living. There
was so much beauty, so much potential, that at first they kept it a
secret. Inevitably, word got out. Though the technology has evolved,
the tools of the craft of glassmaking are fundamentally unchanged since
An important influence in the tools of glassblowing are the methods
developed that require the use of these tools. The earliest method used
to create glass pieces is called core forming. Core-forming involves
a sand/clay core that is wrapped in glass (3). The core is formed around
a rod called a pontil.
Among several techniques used in core-forming, trailing was the most
popular way of applying the glass to the core. In this method another
pontil was used to gather glass and wrap it in strands around the core.
Then the glass was distributed evenly around the core with a paddle.
The glass was also marvered: rolled on a flat table, to achieve cylindrical
form or to correct the position of the glass.
Once the main process was over,
a separate gob of molten glass could be touched to the glass and then
stretched with tweezers to a second connecting point to form a handle
(4). After the glass had cooled, the core was chiseled out and the glass
exterior was polished using a sandstone or pumice stone. (4).
The tools used in this early method (such as pontils, paddles and marvers)
are still in essence a huge benefactor of glassmaking. Glass at this
point was laborious to make and costly, and so new methods were developed
that make glass more broadly available.
Slumping, a method that involved draping the glass into or over a mold
sped the glassmaking process considerably. Most importantly it removed
the need for a core. Core forming was not forgotten; as it was still
being used around 30 BC (2). An important method of forming the glass,
called casting, was developed along with the invention of the blowpipe.
Casting allowed the gather of glass to be lowered into a mold, and be
blown to take on the mold shape. This method was made possible by the
invention of the blowpipe.
The blowpipe is said to be 'one of the most significant advances in
the history of industry
' (1). It may have been discovered around
1 BC (2) by a Syrian glassworker, who found that if one blew into a
hollow pipe toward the glass gob on the other end, the glass would inflate.
This revolutionized glass forever, changing the term 'glassmaking' to
'glassblowing' and allowing glass to be made more easily than ever.
The first blowpipes were made out of hardened clay, because it was the
easiest material to come by (5). During the 4th century BC there were
iron pipes made (6), and eventually copper pipes. These pipes were only
good for several uses because the material couldn't withstand high temperatures
These days we use materials that can stand up to the heat and wear that
accompanies the glassblowing art. Manufacturers use steel as a base
for all of their blowpipes. A lot of consideration and re-engineering
has evolved the blowpipe so that it may overcome any problems while
in use and stay the heart of all glassblowers.
One very important type of steel used is called D2 steel. It is produced
by air hardening a mixture of high carbon/high chromium steel. Its properties
include resistance to wear, corrosion, and extreme heat (7).
Fred Metz, who runs a tool company called Spiral Arts Inc., currently
makes the best blowpipes in the country (8). Over the years, the company
has changed the (steel) alloy content of the pipes, reduced/eliminated
scaling in the pipes (flakes of iron oxides that are caustic and have
negative effects on the glass (9)), improved the balance of the tool
for better handling, changed the mouthpiece, contoured the receiving
end so that the glass can be collected easier
So as you can see, there is a lot that can go into a single tool. Another
still important tool is the previously mentioned pontil (or punty).
This tool is special because it works closely with the blowpipe.
The pontil is a long solid or hollow rod used to hold a piece during
the finishing process (10). Pontils are one of the first tools used
by early glassblowers, and today they still hold significance. They
are very capable tools and similar to the blowpipe, but are generally
not blown into.
A primary use of the pontil is to transfer glass pieces. The transferal
of glass is a vital process, and it can be very dangerous if performed
wrong. There are two instances where a transferal will be used; during
the middle and at the end of the production.
When making an open-mouthed object, like a cup for example, a punty
is attached opposite the blowpipe so that the blowpipe can be cracked
off and the piece opened up. Once a piece is complete, it is then cracked
off of its pipe onto a cushioned surface so that it can be annealed.
If the transfer or cracking off is done wrong the piece could shatter
or leave a deep scar.
There are several residual effects of removing a punty that have been
recorded throughout the ages. The types are bare iron, sand covered,
and glass tipped; each leaving their own unique scars (11). Glass tipped
is the most prevalent type today, because the scar can be easily removed
by reheating and smoothing.
In the year 1697, Europe invented a tool called the 'snap' that removed
the scarring issue altogether (12). A snap is a kind of punty for working
the neck on bottles, with a cup to take the base of the bottle and arms
with curved grip ends to hold the neck (13). The design allowed the
piece to be removed with no residual effects (compared to the use of
a pontil), because the piece was solely resting in a 'cradle'. There
were many attachments for the snap so that it could handle different
sized pieces (12).
Traditional Snap (13) ____________________________________________"Hot
The snap had mostly replaced the
pontil during the 1850's, but both are equally used today. A company
called Arrow Springs produces its own line of snaps, with the patented
name 'hot fingers' (14).
As methods were developed, tools were made to meet the standards. Tools
were needed to form the glass in specific ways, and they needed to be
built out of the best material. The tools to shape the glass have been
used in many ways, using their unique sides and shapes to new advantages.
A collection of the most important tools and their origins/functions
are listed below
The oldest tools are basic elements that are essential to the formation
of the glass; the human eye and gravity. The human eye is the most important
tool, able to identify the temperature of the glass, tiny imperfections,
and to hold the vision of the finished piece. The eye is also important
because it can observe. Observation has been used when attempting to
learn the craft, but also in the old days as a 'spy technique'. When
somebody wanted to know how things were done elsewhere, they had people
go and carefully observe a process and bring back the knowledge to be
explained. This is how many countries learned the art and methods of
Another very important tool is gravity, and every glassblower tries
to use it to their advantage. It is necessary to keep the glass in its
center of gravity before tooling it in any way. Gravity also allows
the glass to be drawn out to a desired form and provides dynamics in
The next is a physical tool called a marver. This is a table made for
rolling the glass to achieve cylindrical shape, to re-position the glass
on the rod, or to collect extra glass for decoration. Marvers were first
made from a flat slab of marble, and was later on made of graphite or
a metal (most commonly steel) (5). Graphite and steel are used because
of their heat tolerance (9).
Forming blocks are made to spherically shape a gather of glass (Fig.
A). Walter Evans, owner of the Cherrywood Mold Shop in Kenova, WV (15),
made the best wooden tools for glassblowing until he retired and passed
his knowledge on to his successor Gary Guydosh, who runs Hot Block Tools
(16). Gary has kept up Evans' tradition of using Black Cherry wood in
all of his pieces. This wood is chosen for its tight, even grain which
holds in water much better than other wood (9). The tool itself must
be water- logged to be kept in constant use or else it will crack.
Paddles are thin blades with handles (Fig. B). These have also been
used since very early glassmaking methods were established, like in
the core-forming method to spread the glass about the core evenly. This
very simple tool can be used more craftily nowadays; to fashion as a
heat shield to protect delicate hands, or to gently flatten the rim
of an object. Thin metal-bladed paddles are a traditional Italian type
tool (9), but they are also made out of graphite and wood.
Newspaper can be used as a close-up hand tool that acts as a forming
block. The newspaper has a high heat resistance if it is folded correctly
and if it is constantly damp. The newspaper must be folded 4-5 times
to provide ample distance between the glass and your hand. It must be
damp at all times so that it doesn't catch on fire when applied to the
glass. There is a legend that NY Times newspaper is the best for this
The Jack is the most versatile and important hand tool (Fig. C). A jack
is a hairpin shaped tool that springs open and has long blades that
are parallel about 12-15" long used for shaping glass (9). Wooden
tipped jacks are best for reaching deep into a piece without damaging
it. Also, wooden tipped jacks do not draw as much heat from the piece
as steel jacks. For this reason wooden jacks are often used when the
glassblower needs to work the piece longer and needs to sustain the
heat of the piece. This tool can be used effectively by a skilled artisan,
who can utilize every side and shape of the tool. The best jacks are
made by Jim Moore (8).
Tweezers are exactly what they are, tweezers (Fig. D). They are long,
widespread tools with bent tips for better grip (9). They are used for
delicate maneuvers. This tool was most likely adopted from another craft
or was manipulated from a household item.
Shears are used to cut gobs of glass off of a piece or to guide a pontil
into place (Fig. E). Shears are useful when a bubble must be removed
from a piece because it can draw out the designated section of glass
to be cut off. They most likely evolved from early sheep shears that
share similar design. Diamond shears are designed to cut off the large
amounts of glass, and straight shears are meant to cut linear lines.
Straight shears are equivalent to scissors, which are another tool used
by glassblowers (5).
A forming tool is similar to a wood jack in looks and in purpose, but
forming tools are generally for more delicate work, like gently shaping
the stem of a goblet.
Jim Moore (8) and Carlo Dona (17) are two of the leading manufacturers
of glassblowing tools today. They offer a wide selection of the best
glassblowing tools. Specifically, Moore's jacks and Carlo Dona's blowpipes
are some of the best in the market. Dona stands firmly behind his families'
legacy of "offering tools whose designs have been refined by the
world's best glass blowers for over 80 years." (17). Both Moore
and Dona have built everlasting tools that have been tailored to satisfy
the artisan and the improvement between their tools and that of ancient
times surely show a 'state-of-the-art' transition.
Another important factor that has certainly changed glassblowing throughout
the ages has been the development of the furnace. The furnace is used
to melt the glass and to keep it at a workable temperature. The earliest
furnaces were made out of clay and were heated by wood. The furnaces
would've been built next to a large fuel source (in this case heavily-wooded
area), because it could not operate elsewhere. There were workers whose
job it was to fuel the insatiable furnace. This job was very important
because the workers needed to know just when to add wood to keep the
temperature consistent (18).
Thomas Percivall invented a furnace in 1615 that could be fueled by
coal. His invention was badly needed at the time because all of the
wood being used to run the glassblowing shops was being put towards
England's naval armada. Coal was able to heat up to higher temps more
quickly than a wood-fired furnace, which reduced the attention that
the previous workers gave when hand-feeding the wood (18).
When glass was being brought to the New World, early James Towne (VA)
workers incorporated a separate furnace in their glassblowing process.
This furnace, called the 'fritting oven' was used to pre-heat a batch
of glass before being dumped into the main furnace. These furnaces were
discontinued after a time to streamline the glassblowing process (19).
There were quite large furnaces made, especially in the 1900's because
of industrialization. One example, found as a model in the Corning Museum
of Glass, is a 16-pot furnace. This was a gigantic dome-shaped furnace
that contained 16 crucibles that contained sometimes different batches.
The crucibles contained 800-2000 lbs of glass, heated by the furnace
at nearly 1280 degrees centigrade. There were teams operating at each
entrance to the furnace all the way around (2). This is a more recent
example of large-scale production that was not mechanized.
The furnaces that are manufactured today are built in consideration
of many aspects. They are not only built to heat up the glass, but engineered
to be efficient, safe, and durable. John Chiles; a long time glassblower
and equipment maker, has built some of the most efficient furnaces around
today. His oldest furnace, built 20 years ago, is still working just
as well as when it was first installed; along with every furnace that
he's sold since (20). He stands by his work with confidence and pride.
The design of a furnace starts from the inside out (19); starting with
the crucible out to the fire-bricks and to the steel frame that supports
the furnace. John is able to cast almost any size furnace in his shop.
He provides his customers with molds to cast new size doors, a guide
for maintaining the equipment, and a wholly inclusive instruction manual
(20). This makes for a more versatile product that ancient glassblower
would never have dreamed of.
The general layout of one of his furnaces starts with the interior size
based on the size of the crucible. Then there is a layer of fire-brick,
with 10" of 12-lb high alumina insulation backing it. The excess
amount of insulation makes for more efficient heating. Also the interior
has a refractive surface that bounces the hot red-waved particles inwards,
allowing for more efficient heating. Following the alumina insulation
may be blocks of heat-resistant insulation; all wrapped in a cast high-temperature
concrete case. Everything is supported by a 2" steel frame (19).
One neglected important factor is the combustion and safety systems
on the furnace. These systems are important when operating the furnace,
and among other things they regulate air and gas input, controls the
John also makes glory holes, also called reheating furnaces. He mentions
that glory holes have only been around for 35 years; and that furnaces
doubled as glory holes when glassblowing was still young. His glory
holes also provide excellent insulation for maximum efficiency, and
operate on separate burners from the furnace so you can shut one system
down and not the other (19).
The last step of a glassmaking process is done in the annealing oven.
The annealing oven is used to bring a recently finished piece slowly
down to a workable temperature. The temperature starts at 1000 degrees
Fahrenheit and is lowered to about 400 degrees to remove stresses developing
in the pieces that had been cooling outside of the furnace during production.
If the pieces were not annealed, they would shatter. An early method
of annealing was to bury the piece in sand until it could be handled
All of this big equipment is being built with efficiency in mind, in
comparison to the early days of glassblowing when they concerned themselves
with just getting things up to temperature. Using fundamental laws and
modern technology, we've come up with new efficient equipment; like
the electric appliances. Electric furnaces (22) and glory-holes (23)
are in the future of glassblowing. They are built with quietness and
consolidation in mind. But comparatively, current propane furnaces will
still be around for some time, because of the superior circulation within
the furnace that the electric furnace cannot match yet (19).
Parallel to the blowpipe having a huge effect on glassblowing, glass
has changed largely with industrialization and our basic understanding
of chemistry. Glass was first industrialized by Edward Drummond Libbey
in 1888. He started his factory in Toledo, Ohio and named it the Libbey
Glass Company. The factory specialized in fine-cut glass (18).
When Libbey was successful enough, he decided to invest in a new idea
proposed by Michael J. Owens; a good friend and employee of his. He
built an invention that could produce a large amount of molded glass
pieces in record time. It was called the Owens Bottle Machine. His machine
worked, and Owens success was deemed the 2nd major victory in the history
of glass industry (18).
Owens Bottle Machine comprised of a main vessel that contained a large
pot of molten glass. The machine had 15 rotating arms, each with an
identical mold built in. The machine would insert a measured gob of
glass into the mold, and then the glass was air compressed to fill the
mold. In this fashion, Owens' machine could produce 1,000,000 bottles
every week! (18). Figuratively, making 450 bottles by hand would take
6-hours. Comparatively, Owens' machine could make that many bottles
in 15 minutes and with today's machines 7 minutes (2).
Industrialization has been both a great thing and also a bad thing.
It is a bad thing because it drew away from the artistic glass scene
for a while, making it harder for off-hand glassblowers to make a living.
But at the same time, it provided the world with much cheaper glass,
opened up lots of factory positions on the floor, and during the 20th
and 21st century glass became such a huge part of our daily lives that
the demand can't be met any other way.
In this modern age, glass is in a good balance between 'industry' and
'hand made'. The factories produce the glass that we use everyday, and
the off-hand glassblowers are still able to produce beautiful art and
make a living.
In 1962, The Studio Glass movement, started by Harvey Littleton and
Dominick Labino had gotten individuals into shops of their own where
they were able to melt and create glass their own glass (5). This movement
has inspired people internationally to get into the groove of glassblowing,
making one-of-a-kind pieces that would only be possible with the developed
tools we have today (2).
Now it is the 21st century, and the glass industry is booming. With
large scale productions and small scale wonders, new pieces are being
created every day for practical uses and for extraordinary purpose.
The glass artisans have inherited the best tools to create the most
spectacular art that humans have ever seen. When we look at a glassblower
today, we can see 4,000 years of history: in their eyes, right down
to the very tools in their hand.
Fig. A Forming
Fig. B Graphite Paddle (8)
Fig. C Steel
Fig. D Tweezers
Fig. E Diamond
(1) Hoyt, Homer L. Glassblowing: An Introduction to Solid and Blown
Glass Sculpting. Crafts and Arts Publishing Co. Inc., 1989. Print. Preface
(2) Randall, Hugh G. Self-conducted tour; notes taken. Corning Museum
of Glass. Corning, NY. November 22, 2009.
(3) Paterson, Alan J. How Glass is Made. Threshold Books Limited, 1985.
(4) Taylor, Mark, and David Hill. "Roman Glassmakers Newsletter
7." Roman Glassmakers Home Page. Jan. 2005. Web. 30 Nov. 2009.
(5) Wikipedia Foundation Inc. "Glassblowing -." Wikipedia,
the free encyclopedia. 13 Nov. 2009. Web. 28 Nov. 2009. <http://en.wikipedia.org/wiki/Glassblowing>.
(6) "BLOWPIPE. Early glass blowerÃ?s pipe of cast iron."
Antiques, Art and Collectibles - What's it Worth? | WorthPoint. Web.
28 Nov. 2009. <http://www.worthpoint.com/worthopedia/blowpipe-early-glass-blowers-pipe-cast-iron>.
(7) "D2 Tool Steel." D2 Tool Steel. CRS Holdings Inc., 1 July
2000. Web. 30 Nov. 2009. <http://cartech.ides.com/datasheet.aspx?i=103&e=263&c=techart>.
(8) Moore, Jim. Jim Moore Handcrafted Glass Tools. 2009. Web. 30 Nov.
(9) Firth, Mike. "Glossary of Tools & Equipment for Glassblowing."
Transfer file index.htm to start.htm. Web. 30 Nov. 2009. <http://mikegigi.com/glostool.htm>.
(10) Firth, Mike. "IGCB." Transfer file index.htm to start.htm.
Web. 30 Nov. 2009. Firth, http://mikegigi.com/glosigcb.htm#P
(11) Lindsey, Bill. "Pontil Scars." The Society for Historical
Archaeology. 14 Nov. 2009. Web. 28 Nov. 2009. <http://www.sha.org/bottle/pontil_scars.htm>.
(12) Lindsey, Bill. "Bottle Bases Page." The Society for Historical
Archaeology. 18 Nov. 2009. Web. 28 Nov. 2009. <http://www.sha.org/bottle/bases.htm#Snap%20Case%20&%20Sabot>.
(13) Firth, Mike. "Glossary of Tools & Equipment for Glassblowing."
Transfer file index.htm to start.htm. Web. 30 Nov. 2009. <http://mikegigi.com/glostool.htm>.
(14) "Arrow Springs Holding Tools." Arrow Springs' Home Page.
Web. 30 Nov. 2009. <http://www.arrowsprings.com/html/holding_tools.html>.
(15) "Glassblower.Info - Cherrywood Mold Shop - Kenova, WV."
Glassblower.Info - Glassblowing Information, Photos, Videos. Web. 30
Nov. 2009. <http://www.glassblower.info/one.php?id=cherrywoodmoldshop&map=no>.
(16) Guydosh, Gary. Hot Block Tools. Web. 30 Nov. 2009.
(17) "About Carlo Dona Tools." Spiral Arts. Spiral Arts Inc.,
2006. Web. 02 Dec. 2009. <http://www.spiralarts.com/about/about-cd.asp>.
(18) Diamond, Freda. The Story of Glass: The Glass Bubble. Harcourt,
Brace and Company, NY. 1953. P. 38, 51
(19) Diamond, Freda. The Story of Glass: Glass in the New World. Harcourt,
Brace and Company, NY. 1953. P. 59-60, 82, 84-85.
(20) Hot Glass Blowing Tools, Equipment and Supplies - HUB Consolidated.
Web. 04 Dec. 2009. <http://www.hubglass.com>.
(21) "John Chiles Interview." Personal interview. Dec. 3 2009.
(22) "Glass blowing equipment - Furnaces - Denver Glass -."
Denver Glass Machinery, glass working equipment for the professional.
Web. 01 Dec. 2009. <http://www.denverglass.com/furn.html>.
(23) "Electric Glory Hole Specifications." At Electroglass
we manufacture state-of-the-art, electric, glass melting furnaces, fusing
kilns, electric glory holes, and annealers. Web. 30 Nov. 2009. <http://www.electroglass.com/gloryholespec.html>.
like to thank my mentor Michael Egan and his wife Angela for granting
me the privilege of working with glass in their shop, and for Michael's
close guidance throughout my project. They are a great team and I have
learned a lot from both of them."