- A
- Acetylene
- A pure gas compound (HC2H) mostly made by man and supplied in tanks for
use as fuel for a very high temperature (4000F) flame for welding and metal
cutting. Dangerous in that it is explosive over a wide range of air/gas
mixtures. 2009-07-26
- Acid
- Chemicals which have H in their designation. Not a lot of use in
glass work. Weak acids are used for cleaning glass, most commonly
vinegar containing citric acid. Strong acids include Hydrochloric (HCl),
Sulfuric (H2SO4), Nitric (HNO3) and Hydrofluoric (HFl) Hydrochloric
acid is sold as pool shock in grocery stores. Sulfuric acid is sold to
charge car batteries and is used to clean metals.. Both are very
strong and must be handled with care, damaging clothes and concrete.
Nitric acid is harder to get. Hydrofluoric acid is incredibly
dangerous because it penetrates the skin without pain and destroys the bone
underneath. Fluorine gas given off in reactions is also dangerous. It
is one of the few acids that will dissolve glass and thus has been used to
selectively remove parts of designs not protected by wax or asphalt.
Requires great care and good ventilation for proper use. 2006-10-03.
-
Air
- Air is a material for glass BLOWING, amazingly enough,
but it is also used for cooling pieces as well as being
supplied under pressure to burners and moved for
ventilation. Burners
Ventilation
- Alumina, aluminum oxide (Al2O3 )
- "Makes glass stronger and blunts attack by acids and alkalis and
increases elasticity of glass." AmGlPrac 2005-02-09
- Antimony oxide (Sb2O3)
- An ingredient in glass making when mixing batch. Further
information at batch.htm
- Asbestos
- A fibrous mineral previously mined and much used for
heat and electrical insulation. Unfortunately, it breaks
down and produces long, thin, essentially invisible fibers
that when breathed are taken into the lungs and encased
with flesh, making them non-removable while they reduce
the capacity of the lungs (asbestosis.) Ceramic fiber
blanket is an alternative but reportedly has some of the
same problems, especially once heated.
- B
- Barium carbonate (BaCO3)
- An ingredient in glass making when mixing batch. Further
information at batch.htm
- Batch
- Glass can melted from broken glass cullet or be
made from a mixture of chemicals, mostly sand. Batch can
be mixed by the worker or bought. Most commonly used
bought batch is from Spruce Pine Batch Co. although several other
companies have started offering batch.. Mixing
batch requires care as many ingredients are poisonous or
lung damaging. Sand, Lime, Limestone (Calcium Carbonate),
Soda (Sodium Carbonate), Soda Ash, Potash (Potassium Carbonate), Lithium carbonate,
Feldspar, Sodium nitrate, Zinc oxide, Barium carbonate,
Fluorspar, Antimony oxide, Arsenic. Further information at batch.htm
- Bead Board
- The white fluffy firm plastic insulation often called
Styrofoam. Bead board is made by steam heating hard little beads
in a mold where they fluff up and bond together. Much easier to find. Styrofoam is filled
with bubbles and harder and is made with a chemical mixture. Mostly
used like lost wax in casting.
- Bee's Wax Beeswax
- Used to lubricate jacks and other tools. From fabric
stores or use a candle. Carnauba wax is harder. Wax
mixtures, especially on older steel (vs. stainless steel)
jacks are a heartfelt topic among gaffers.
- Blocks
- Blocks are chunks of fruitwood, most commonly cherry but
also pear and apple, which are carved to a shape useful
in forming glass and then soaked in water until
waterlogged. The steam from the water and the carbon that
forms on the surface makes a durable tool. Usually will
crack if allowed to dry out. Wooden rods and paddles are
also used the same way. Walter
Evans makes blocks for many studios. Blocks, Paper & Wood
- Boric Acid, Borax (H3BO3, Na2B4O7
+ 10H2O)
- Ingredient in making glass. Especially important in making
borosilicate low expansion glasses such as Pyrex which withstand heat shock.
Makes glass stiffer to work. 2005-02-09
- C
Castable
- Shorthand name for high temperature refractory
materials that are in powder form, mixed with water and
poured in a mold for forming, as opposed to rammable,
brick, and block. Materials may result in the equivalent
of an insulating fire brick or solid high temp fire brick. Used for
building high temp equipment. Refracto.htm
- Ceramic fiber blanket, board & paper
- Modern industrial high temperature insulation to replace
much more dangerous asbestos. Available in several forms
and several temperature ranges. Refracto.htm
- Cold Working
- The general name for sandblasting, grinding and polishing
the glass. While many artists use the procedures of cold
working as part of their artistic creation, most would
prefer to avoid the labor intensive process of grinding
off punty marks and polishing the result.
-
Colloidal silica
- used
as a rigidizer for frax and for making molds. "micro-fine particles of
silicon dioxide(SiO2 ) dispersed in water. 30%-40% SiO2 is
common. If the particles are smaller than
about 7nm [0.000000007m 0.00000027"] the sol is almost as clear as water.
From 10 to 30nm there is a characteristic opalescence or translucency when
seen it, and above about 50nm the appearance is white and milky."
colloidal silica site
- Color bars
- Glassblowers using moderate amounts of color in their
glass buy bars of concentrated colored glass about 1"
in diameter and a foot long. This is cut in smaller
chunks and melted, crushed or pulled. Sold by the kilo
for a full bar, cost is effectively $1-3 per inch ($17-48
per kilo.) Those using more color tend to melt their own
to reduce cost. Color
- Crystal
- When being precise by modern definition, glass with approximately 20-35%
lead oxide added. This makes a soft clear glass that reflects and
refracts light brilliantly, making cut crystal sparkle. The glass
also, when thin, has a distinctive bell-like ring when gently struck and
will "sing", as in a glass harmonica
when rubbed on the rim with a wet
finger. Less precisely, any clear uncolored glass that resembles rock
crystal (clear quartz, the original crystal balls) so fine clear glassware
is referred to as crystal and the original crystallo (sp) from Murano Italy
was made with very pure (no iron) flint but had no lead which was added in
England.
- Cullet
- Broken glass, which melts with less energy than batch. Can be
remains of previous work, bottle or window glass, or purchased. The
latter two may need chemical additions to make more
workable. Available from Gabbert
Cullet from pressed glass factory operations and in both cutoffs and
custom pellets from Spectrum's stained glass operations.
Slag
- D
-
E
- Enamel
-
Glass color ground up and mixed with other chemicals to
lower the melting point to apply to metal
or glass surfaces to melt it onto the surface without melting the glass
below. Frit
is just ground glass, melting at the same point.
- F
- Feldspar
- An ingredient in glass making when mixing batch. "a silicate of alumina
and either potash or soda (or both)", so is a natural glass of a not
exact formula, roughly 65% silica, 20% alumina, 10% soda or 12% potash. Further
information at batch.htm
- Fire brick
- A brick made to withstand high temperatures, costing more
the higher the temperature, from $1.50 to $20 a brick.
Usually very hard and heavy, a poor insulator. Available
in many shapes. Used for furnaces mostly. See also Fire
brick, Insulating. From A.P.Green, Mexico MO and local
offices, National Refractory, see Refractory
in Yellow Pages..
- Fire brick, Insulating
- A very light, soft, easily cut, high temperature material
than can form structural walls and backup hard fire brick.
- Fluorspar (CaF)
- An ingredient in glass making when mixing batch. Further
information at batch.htm
- Frit
- Chunks of broken glass the size of raisins to grape nuts,
bigger than powder. Can be bought, for smaller
quantities, usually made with crusher if color bar is on
hand.
- Fuel
- Glass melting takes a lot of fuel, most often propane and natural gas in
modern studios, and natural gas in factories, but originally wood until it
came into short supply then coal which requires special covered pots.
- G
- Gather
- Both the name for going to the furnace to get glass (to
gather, gathering) and for the glass gotten (first
gather, second gather). The end of the pipe or punty is
lowered into the glass and turned to drag the glass
evenly around the pipe or previous gather. The analogy
most often used for the process is turning a spoon or old
fashioned wooden pickup in honey, keeping it turning to
get to the plate. However, gathering glass involves stuff
that is over 2000ºF that will melt and deform the
previous gather if done too slowly (not to mention set
clothes smoking.)
- Glass
- Well, golly gee whilikers, really? Glass. A material used in
glassblowing? Well yes. Common glass is made from sand,
limestone, and soda ash with other chemicals to make it easier to melt,
remove bubbles, de-color it to clear or give it color, and so forth.
Common window, bottle, and glassware glass is soda-lime. If borax is
substituted for the soda-lime the result is borosilicate, sold as Pyrex,
which melts at a higher temperature, expands and contracts less, and is less
likely to break with abrupt temperature changes, so it is used with
cookware, scientific lab ware and telescope lenses. There are many
specialty glasses for optical clarity, toughness, unique light transmission,
and so forth. Batch, Cullet,
Crystal
- Glass Clay
- Glass clay is a relatively new product that performs somewhat like pate
de verre and precious metal clay while allowing making of forms by modeling
rather than having a high temperature mold to hold the glass.
http://www.glassclay.com/ pate de
verre 1 2
2011-07-23
- Graphite
- A form of carbon that takes the form of flat plates that slip easily
over each other, thus making a lubricant. In glass work graphite is
used for blocks and paddles because it makes a smooth surface. It
conducts heat very well, so it does not chill the glass as much as marble or
metal might. It also conducts electricity. It can be used for
molds, with care, because if held at too high a temperature it will
sublimate or burn. 2006-10-03
- H
Hydrofluoric Acid
- VERY DANGEROUS "A volatile, colorless and highly corrosive acid used as
an agent to etch glass. Pure acid dissolves glass leaving a bright
surface [used for cutting back a design] Mixed with sulphuric acid it
produces a high gloss on lead glass; mixed with ammonia, the neutralized
acid leaves a frosted finish." Collectors Encycl.of
Am.Art.Glass p.226 MF: DANGER: HFl silently penetrates exposed
skin and begins attacking the bones, only causing pain when too late and
requiring extreme measures of calcium ingestion to save life. Fluorine
gas is a lung damaging toxic material. 2008-05-21
- I
- Ingredients
- Among the ingredients of glass are Sand,
Limestone, Potash,
Soda Ash which are also discussed the mixed product batch
- Insulating Castable
- Castable Refractory with insulating
values similar to insulating fire brick
- Insulating Fire Brick IFB
- A lightweight fragile fire brick that insulates against
high heat. Will withstand various max. temps up to about
2500F, while non-insulating firebrick can be had up to
3500F Refractory
- Investment
- A white powder mixed with water to make high temperature molds for
metals (and glass). After heating it washes off the piece.
Metal Molding 2003-02-05
- J
- K
- L
- Latex
- A white thick liquid containing natural rubber in unvulcanized form that
can be brushed on in thin layers to build up a mold around an original, the
mold then can be used to make copies. The dried latex is amber in
color, is flexible and reasonably tough. Used for
plaster copies, sulphides, and silica/plaster molds. 2003-02-05
- Lead Oxide, Lead (PbO, Pb
- When added to glass, most often clear crystal, gives a
weight to the glass which makes for a clear ringing tone
when struck and a brilliant reflection when cut. Also
extends the working range of glass, so colors often have
a considerable percentage of lead so they will work with
a wider range of COE. Lead is considered a health hazard and must be
tested for on food surfaces in California in particular. Lead in glass
is less risky than lead paint which is less risky than exposed lead in
stained glass came and some solder. "the U.S. safe limit of 0.06% for
paint. Lead is a neurotoxin. It causes damage by mimicking helpful
metals found naturally in the body, such as calcium, iron and zinc.
Lead displaces those and distupts brain circuits. ... New research suggests
there is no safe level of lead exposure." Wall Street Journal, Aug.3 2007 p
A5.
Litharge Red Lead
- Lime, Limestone (Calcium Carbonate)
- An basic ingredient in glass making when mixing batch.
Counter-balances soda ash or potash
which lowers melting point but increases ease of attack on the glass by
water. Further
information at batch.htm
- Litharge (PbO)
- Lead monoxide. Lead oxide
- Lithium carbonate (LiCO3)
- An ingredient in glass making when mixing batch. Further
information at batch.htm
- M
Metal
- In the jargon of the craft in the glass factory the stuff worked which
avoids any confusion with "get me a glass" and "put up the glass we blew
this morning", thus "we had good metal by 8 am today"
White metal is clear glass; opal is opaque
white glass. 2008-05-21
- Metal Oxides Metallic Oxides
- When a list refers to the color supplied by selenium or cobalt or the
qualities of adding lead, it should be understood that always a salt or
oxide of the metal is referred to not the pure metal (with the odd exception
of gold). Cobalt may be added as cobalt oxide or cobalt carbonate.
These mix with the silicon oxide (sand) that forms the bulk of glass mix.
2008-05-21
- Mud
- The name for the strange mixtures of wax, oil and
solvents to coat jacks, especially the old iron ones (modern
ones are stainless steel) to reduce chatter and chill
marks and make for smoother working. Plain beeswax or carnauba
usually works fine.
- N
Natural Gas
- One of two common fuels, with propane, used in glass blowing studios.
Glass factories have often located to take advantage of local availability of
natural gas, thus northern Ohio and West Virginia. Natural gas is
delivered at low pressure in most urban areas and at higher pressure in
industrial areas.
- Newspaper
- Used for shaping glass when formed, wetted and held in the hand, to
replace a mold or block. More
- Nitre
- Sodium Nitrate, used in making glass. Forms
small bubbles into large to fine the glass.
- O
- Obsidian
- A glass made in volcanic flows under proper conditions.
As a glass, it has no preferred cleavage and thus flakes
off in conchoidal form, forming very sharp edges with a thick center for weapons and tools used by natives.
A mixture of about 75% Silicon Dioxide with Iron and Magnesium oxides.
Deteriorates in presences of water to form perlite.
WikiRef Because content varies, so does melting point, but
behavior and temperatures reported suggest it behaves like borosilicate
glass, not melted at 940C (1724F) and melted and deformed but not flattened
at 1080C (1976F) Src, copy on
file 2009-09-24
- Oxygen
- A gas found in the air and an element found in many compounds. Necessary
for life. Used to make flames burn more intensely than with air which
is 80% nitrogen that does not assist burning. Commonly used in torches
with acetylene for welding and with
propane or natural gas for glass, required for
working borosilicate. Occasionally used to boost heat in furnaces. Supplied
in dewars, in high pressure tanks, and by
generators. 2009-07-26
- P
- Paper
- Paper is used in the form newspaper for blocking, in
rolled up rods for pacioffis and
of course in support good old reading material and pictures of glass.
2006-06-29
- Parison
- name for shaped blob at end of pipe in early working stages.
- Perlite
- Used as a refractory insulator by glass workers. A fluffy white volcanic glass
product which is expanded by heat and sold cheaply at garden supply places
as an aerator for potting soils and also used as a lightweight aggregate for
concrete and plaster. "A lightweight material prepared from volcanic
lava,..." Perlite
Institute - Basic Facts about perlite
- Plaster of Paris
- A white heavy powder that, when carefully mixed with water, produces a
creamy
thick pourable mixture that can be used to make molds which can be used to make copies
of the original. Once set, plaster of Paris is insoluble in water.
For more information see Metal Casting. Do
not buy more than can be used in a few months as the powder absorbs moisture
from the air and loses its ability to set. Other materials called plaster
exist. 2003-02-05
- Potash, Potassium Carbonate (K2CO3)
- An ingredient in glass making when mixing batch, an alternative to
soda ash. Further
information at batch.htm
- Propane
- One of two common fuels, with natural gas, used in glass blowing
studios. More commonly used in rural areas where natural gas is not
available, may be okay (as in Dallas) in a large tank where natural gas
delivery is inadequate for glassblowing. A mixture of petroleum
compounds that liquefy under slight pressure and become gas at room
temperatures. Supplied in thin wall metal tanks or delivered and
stored in larger tanks. About 250 psi in storage, reduced by
regulators for use. 2009-07-26
- Q
- Quartz
- The crystalline form of silicon dioxide found in
rocks from which sand
comes by erosion. Melts at a very high temperature and can be worked
like glass to give vessels for processing semiconductor material.
Requires special torches and eye protection to work. 2004-12-07
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Top
- R
- Rammable Refractory
- A product delivered in a heavy paste form that is applied
and hammered (rammed) into place by hand or jack hammer.
Glass workers usually use it for lips of furnaces and
bottoms and use a 3# sledge or similar hammer to mold/merge
it solid. In industry it is used for repairing and
building up high abrasion locations and some can be
applied while the location is relatively hot (several
hundred degrees, not a couple of thousand.) 2001
- Red lead (Pb3O4)
- Form of lead used to make flint glass. "bright red
to orange-red powder, also called minimum, that is used in
the manufacture of storage batteries, lead glass, and red
pigments; a paint made with red lead is commonly used to
protect iron and steel from rusting. Chemically, red lead
is lead tetroxide, Pb3O4 , a water-insoluble compound
that is prepared by the oxidation of metallic lead or of
litharge (lead monoxide); the commercial product
sometimes contains litharge as an impurity."
Lead
- Refractory
- Any material that withstands the high heat needed for
melting glass (also steel, etc.), the two most common
being clay and ceramic fiber substances. Special clays
fire up to form bricks that do not deform in the heat. If
previously fired clay (grog) and organic material is
added to the mix, insulating firebrick is created by the
empty spaces in the fired clay. Ceramic fiber is a result
of space research and insulates. Two other refractories,
known to gardeners, and sometimes used as insulation are vermiculite, which is expanded mica, and perlite, from lava. Refracto.htm
- S
- Sand
- Mostly silicon dioxide in the form of quartz. An ingredient in glass making when mixing
batch. Further
information at batch.htm Pure white sand
has very low iron content which is desirable for making glass without color.
2004-12-07
- Silica (SiO2 melt:3133F)
- The pure form of silicon dioxide, also referred to as silica flour.
Usually a fine white powder, it is used in foundry work for making thin
shell metal casting molds with colloidal silica, a
liquid suspension in water. Silica is damaging to the lungs.
- Silicon (Si sg:2.33 melt:2605F)
- The element, one of the most common on earth, that makes glass as the
oxide and in very pure form (99.999999999%) forms the
basis for the modern semiconductor industry.
As much as you ever
wanted to know 2004-12-07 Not silicone
- Silver Leaf, Foil, Metal (Ag sp:10.49)
- Pure metal, used for inclusions and decorations on glass as well as
being worked with jewelers methods and formed around the glass. Leaf
is very thin, foil is thin, the latter being more common in glass work
because discoloration near the melting point of silver (1761F) which is
lower than molten glass. 2004-12-07
- Silver Nitrate, Chloride, & Bromide (AgNO3,
AgCl, AgBr)
- Chemicals used to color glass, especially to provide a
silver sheen to the surface when the salt is reduced to
the metal after application.
- Slag
- Slag is broken chunks of glass which are usually the result of dumping
or breaking up a furnace or pot. Because of odd thicknesses and harsh
edges which catch the light, it has been used for decorative purposes for
centuries. Could be used like cullet but normally
is not as it is the remains of a large mass of glass and is not consistent
or easy to handle. Sold by Gabbert
Cullet and through rock/lapidary outlets. 2009-02-25
- Soda (Sodium Carbonate, NaCO3), Soda Ash
- An basic ingredient in glass making when mixing batch. Further
information at batch.htm
- Sodium nitrate (NaNO3)
- An ingredient in glass making when mixing batch. Further
information at batch.htm Forms small
bubbles into large to fine the glass.
- Sodium Silicate, Water Glass
- A thick clear liquid (as used) available from pottery supply places,
used as glue and rigidizer for frax and in making sand casting molds. It
gets hard on exposure to CO2 in air or directly. A mixture of
silicates with the general chemical formula xNa2O.ySiO2,
forming a clear viscous solution in water.
xrefer - water glass (or sodium
silicate) [NaO2 3.22 SiO2 Initial acidification of
a water-glass (sodium silicate) solution yields Si(OH)4"
Colloidal Silica]
- Steel
- Ordinary steel angle and tubing is used to construct equipment while
stainless steel is used for pipes and punties
and for containers.
- Styrofoam
- Used to make cores for casting furnace domes and for casting glass.
Styrofoam is a (usually) white puffy plastic that comes in two forms - bead
board and cellular foam. Bead board is far more common these days
because it can be made in a simple mold (cardboard box if need be) by adding
steam to hard pellets which expand and stick together. It can be recognized
by the small balls of plastic that are shed and the circles showing on the
surface. Cellular foam has lots of "air" spaces and is less available
because to make it requires a leak proof box that will contain the expanding
foam to restrict the bubble size. The bubbles are made chemically or
can be done with a large air mix. Requires a central installation.
Both types are usually scrounged by glass workers. The board is used
as insulation in flat pieces and furniture and computers come packed with
the stuff - it can be glued with white glue into bigger blocks. 2003-02-16
- T
- Tin Chloride (SnCl)
- One of the chemicals sprayed or blown on hot glass to
iridize the glass, producing the sheen like glass long
buried in mineral rich soil.
- Tin Oxide
- When added to glass batch produces opaque white glass. Further
information at batch.htm
- U
- V
- Vermiculite
- Used as a pourable refractory insulator and component of insulating castable. A fluffy dark gray product made by heating a variety of micacaous minerals and sold cheaply at garden supply
places as an aerator for potting soils; also used as
insulation and as a passive annealer for lampworking. Rumored to
contain fine asbestos particles but true only in distant past of one
mine..
- Viscosity
- A measure of the thickness or pourability of liquids. An important
factor in working and annealing glass Discussed
here
- W
- Wax
- A category of material mostly characterized by a melting point below the
boiling point of water with a glossy surface and a "waxy" appearance. Most
are water repellent and are used for protective coatings, shiny appearance,
and slippery movement. Waxes used in glassblowing include beeswax and
carnauba for tool
edges, and casting wax for lost wax molding. 2003-02-05
- Water Glass
- See sodium silicate
- White Glue
- Usually means common woodworkers glue, like Elmer's Brand that is not
particularly waterproof. Besides wood, it can be used to glue
Styrofoam and is used to hold glass pieces in place for
fusing. glues.htm
- Wood
- Used to make tools which stand the heat because the wood
is soaked in water until water logged and further lifted
from water just before use, so coated with water. Blocks, Paper & Wood
- X
- Y
- Yellow Glue
- A woodworking glue that is more water resistant and stronger than older
white glue. It is not water proof and joints
will come apart if soaked in water. Can be used to glue Styrofoam, but
leaves a tougher joint to attack when shaping.
glues.htm
- Z
- Zinc oxide
- An ingredient in glass making when mixing batch. Further
information at batch.htm
- Zircon
- A refractory material used to seal surfaces of other refractories, to
repair cracks in burner heads, and for lost wax casting of glass and bronze.
Zirconium oxide is available as a slurry for coating models and
painting on surfaces and as a powder to add thickness to casting shells.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Top
Glossary Master List
This page extracted in part from Mike Firth's Hot Glass Bits
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