Warm Glass

1
AMACO Art Glass
2
Natural glass (obsidian) can be found in almost
every part of the world it is formed by volcanic
activity. People have been using this naturally
occurring glass to make tools, beads, and sacred
objects since the stone age. Where and when glass
was first formed from sand, by people is
debatable, but objects from manmade glass can be
traced back 40 centuries.
Raw Obsidian and objects made from it, were some
of the first traded materials known
3
Artists and crafts-people have been making
beautiful glass objects for centuries. Examples
of historical glass can be found in almost every
part of the world.
Amphoriskos 1st century BC
Roman Glass Bottles
Byzantium Glass Plate
Contemporary artist from around the world use
many of the same techniques discussed in this
presentation, to create glass art. Some great
artists to look at are pictured here.
Hans Godo Frabel
Dale Chihuly
4

• Glass has a rigid, crystal-like molecular
  structure, making it hard and brittle, but this
  molecular structure is at the same time random
  and disordered (amorphous) like a liquid, making
  it also transparent.
• Glass in the pure form is silica or quartz, but
  most glass products also contain added
  ingredients which provide various properties. For
  example, Pyrex contains additives which allow it
  to withstand drastic heating and cooling. Other
  ingredients will make glass melt at a lower
  temperature or make it easier to form.
• Soda-lime glass is the most common (90 of
  man-made glass)
• and the least expensive form of glass.
• Everything from bottles, to light bulbs, to
  windows
• are made from this type of glass.
• The composition is 60-75 silica, 12-18 soda,
  and 5-12 lime.
• Other minerals are also added to give glass
  color, such as cobalt
• which makes glass blue, and cadmium which makes
  glass red.
• In making glass art the most important thing to
  remember is that the glass used should all be the
  same coefficient of thermal expansion (COE). This
  means that all the glass reacts to heat and cold
  the same way.

5
What is warm glass?

• There are three types of glass forming methods
  which are distinguished by the temperature that
  the glass is being worked at
• Cold Glass work this includes stained glass,
  etched glass, and sand-blasting.
• Warm Glass fusing glass, slumping glass and lamp
  work are all considered warm and are done when
  the glass is just beginning to become soft.
• Hot Glass This includes glass blowing, furnace
  work, and casting. All are done at the liquid
  stage of glass.

6
AMACO
AMACO provides a variety of glass products and
accessories designed to facilitate the use of
glass in any studio or class room. With
pre-programmed glass kilns, easy to follow lesson
plans, and kits formulated with the classroom in
mind, any art curriculum can expand to include
dazzling glass projects.
Glass Kilns
Fusing and Slumping Kits
Casting Supplies
Lesson Plans
Books
AMACO makes it simple with pre programmed kilns,
easy to follow directions, kit designed with the
classroom in mind and garneted compatible glass
products in a verity of shapes, colors and sizes.
7
Using the kiln to fire glass is almost the
opposite of firing ceramics. In ceramic firings,
the process is to heat up the kiln slowly to the
top temperature and then allow it to cool at a
natural rate. In glass firings, the process
involves heating up the kiln to the top
temperature fast, and then cooling it at a slow
regulated rate.
Typical glass firing program for fusing glass.
Temperature
Time in hours
8
This slow cooling or holding the temperature at
the cooling cycle is called Annealing. This
process allows stresses in the glass to settle
out, otherwise the glass piece would crack and
break when cool. Any computer-controlled kiln can
be programmed to fire glass adequately, however
AMACO glass GSF kilns are pre-programmed with
appropriate annealing cycles. The GSF 670 kiln
has elements housed in the lid, especially
designed to fuse and slump the glass more fully
and discourage air from being trapped in the
finished piece. Glass that is fired in
traditional ceramic kilns will have more visible
bubbles and require the ramp hold program to be
set with appropriate temperatures and hold times.

9
Fusing and Slumping
10
Fusing is the process of heating up glass pieces
to a temperature when they begin to flux and
stick together.
In this process the glass just begins to move, so
edges will smooth out and pieces will become one
flat object, without losing lines of color or
forms. If fired longer or at a higher
temperature, the various colors and shapes will
increasingly blend.
Pre-fuse
After-fuse
Slumping is the process of melting sheet glass
inside or over a mold to give the flat pieces
shape. Decorated glass must be fused first before
slumping. The molds can be made out of fired
clay, sand or anything that can withstand the
heating and cooling cycle.
Pre-Slump
After-Slump
11
Cutting glass to the shape and size required for
each specific design is the first step in
creating the piece. AMACO has a variety of tools
that cut glass in different ways. Depending on
the needs of the design, use one or more of these
tools to cut the glass.
For organic shapes, intricate curves, and
complicated forms, the AMACO Glass Saw is really
the only choice. This piece of equipment, uses a
diamond encrusted blade to cleanly, easily, and
safely cut glass forms.
AMACO also offers a Pistol Grip Cutter which
contains cutting oil in the handle and delivers
the right amount of fluid to cut each piece. Hold
cutter tip directly to glass and firmly press
down, then score a straight, or gently arching,
line with the cutting wheel. Snap the pieces
apart by hand or with the Running Pliers.
12
Amaco's glass jewelry kit comes with a
traditional glass cutter. To use this tool, dip
cutter lightly in oil, and then pressing firmly,
draw/score a straight line. Do not go over score
marks more than once. For straight edges, a
template or straight edge is highly recommended.
Score line
Running Pliers score guide
Tips For a clean cut only score the glass once.
Using the Running Pliers place the line at top
of pliers directly on score-line. By lightly
squeezing the handles, the glass cleanly break
along the score line.
13
Because all AMACO glass products have the same
COE of 90 they can all be combined and intermixed
in a variety of processes like assembling a
collage. Children can create limitless 2-D
designs in glass, focusing on line, color, shape
and contrast.
Fusing
Begin by choosing a bottom piece of glass as the
base and then arrange cut pieces, glass stringers
and chunks in any flat arrangement.
Diluted white school glue (or Elmers) may be
used to affix glass pieces together, stabilizing
the design during transport and loading. (Note
white glue gives off an odor and some smoke
during firing). A second transparent sheet of
glass can be placed on top of the design creating
a thicker piece with a smoother surface. One base
sheet with designs is sufficient and results in a
thinner finished product.
14
Firing
Finished pieces should be placed on kiln shelves,
coated with 1/16th thick kiln shelf wash or
placed on kiln shelf paper.
Glass should to be loaded in the kiln in a single
layer only, without a shelf on top.
This is the fusing phase of the firing. Use full
fuse program on Select Fire AMACO Computer.
15
For slumping, coat slumping form or mold with
kiln shelf wash and place fused design or plain
sheet of glass squarely on the form.
Load molds in single layer only in kiln.
Choose slump (SLP) program on select fire kiln.
This is a slightly cooler and faster firing than
the fusing cycle.
16
Glass Casting
17
Glass Casting
Glass Casting is usually considered a hot glass
method of forming, but is closely related to warm
glass slumping. The process may be as simple as
melting glass in an existing mold, or as involved
as sculpting an original form and creating a mold
to cast in glass. This lesson will explain
mold-making as well as casting.
Mold Making
The first step in this process is to create a
low-relief sculpture no more than 2 inches thick
and no thinner than 1 ½ inches.
Place the sculpture on a non-porous work surface,
such as Formica or AMACO Plasti-Bats.
18
Seal sculpture to work surface so no plaster will
seep underneath as the sculpture might float. Use
small coils of the clay provided in the AMACO
Casting kit.
Next find or construct a container around the
sculpture that will hold liquid. In this project
a plastic food container was used by cutting out
the bottom.
19
Seal the edges of the container, so that the
casting mix will not leak during the pour.
Seal the interior of the box as well.
If the sculpture is made using the clay provided
in the kit, no soaping is necessary. If the
sculpture contains found objects, a thin layer of
dish soap and water can be brushed on the
sculpture allowing it to release easily front the
mold. If making a mold of a non-flexible object,
undercuts must be avoided. If making a mold of a
clay object, there is no need to worry about
small undercuts, but the clay positive (original)
will be destroyed when removed from the mold.
20
Next, using a disposable container, measure out
the amount of water needed for the casting mix.
For mixing the whole amount provided in the kit
the ratio is 4 pints of water to full 10lbs of
casting mix. For smaller batches, refer to the
chart to the right.
21
Because the casting mix contains fibers that help
keep the mold intact during the firing process, a
blunger attached to a drill is used to fully mix
the casting material. For smaller batches a
blender can be used. Mixing by hand is possible,
but all clumps of fiber need to be broken up.
Add measured mix to water gradually by sprinkling
into mixing container.
Let set for 30 seconds and then begin to mix with
blunger.
22
When mixed correctly, the casting material will
be thick and resemble a chunky milk shake.
Pour mix slowly into mold container, taking care
to avoid pouring on the sculpture directly. Tap
mold container gently on the side to force air
bubbles in the mix to rise to the top.
23
Allow mold to set for at least one hour. Once
hard the mold can be released from the container.
Then gently remove the original sculpture from
the mold. Casting mix is soft, so take care to
not damage the mold.
Clean mold of any left over clay, or chunks of
mix that might have broken off. Unlike plaster,
if the mold has an imperfection like an air
bubble or chip this can be repaired after casting
by mixing a small amount of mix and gently
sculpting or dabbing it on with a paint brush
into the defect or cavity.
24
The molds must be completely dry before casting
or they will crack or explode. Molds are best
dried by setting them in a well-ventilated room
for about one week or in an outside sunny
location.
Once the mold is dry, then it can be loaded with
the glass for the glass casting firing.
Make sure molds are Death Valley Dry
25
Packing the mold with too much glass will result
in the glass spilling over the edge of the mold
when firing and making the finished piece
difficult to remove and finish. Filling the mold
with too little glass could result in not enough
glass to fill all details of the sculpture.
This mold was filled too full, it cracked during
firing and the glass spilled out.
For large molds use the process and formula
provided in the AMACO Creative Glass Casting
lesson plan 22. For smaller molds use a 2 cup or
larger measuring container and fill it with one
cup of water. Drop sculpture or the clay from the
sculpture into the water. Mark the amount that
the water was displaced, i.e.. ¼ cup equals 2oz,
multiply ounces displaced by 2.5, this will be
the weight of the glass used to fill the mold.
If the mold has fine details and deep crevices
then select the smallest glass chunks available
to get the best detail.
26
Wash the glass thoughly with dish soap and water
and then again with glass cleaner, then stack the
glass in the mold with shorter pieces at the edge
and taller pieces towards the middle.
Various colored and clear glass chunks can be
intermixed, but note that they do not blend
completely.
Place molds level in the kiln on a bed of sand at
least 1/2 inch thick. Check that the molds are
very close to level otherwise the end piece might
be lopsided.
27
The firing for cast glass can seem quite long in
relation to standard ceramic firings. A typical
casting fire can be 20 hours. For smaller molds
the annealing time is much shorter. The
temperature the annealing is done at is 950
adjust the time according to the thickest piece
to be loaded in the kiln.
Do not unload the kiln until it is completely
cool and the pieces are at room temperature.
28
Unload the kiln and place the molds into a bucket
of water. The water is used to keep dust down and
make cleaning the molds easier. The molds absorb
water and are easy to break away from the glass
pieces. These molds are considered waste or
one-time use only molds.
Glass spurs
Be careful as the glass piece may have small
sharp edges called spurs. The spurs can be
ground down using the diamond pad or a wet
grinder.
29
(No Transcript)
30
AMACO [phone] Technical Support Lori
Jenkins ext. 364 Want to know more? Contemporary
Warm Glass By Brad Walker Corning Museum of
Glass www.cmog.org Glass Making in Antiquity By
Susan Hampton