ponder craft & design

Glass

Materials of the Trade

What are you using your crafted piece for? Does the glass need to be thick, durable, tempered?

Where will your dish spend most of its time – kitchen table, patio, bathroom counter? Will it be kind to the surface on which it will live?

If you find a piece you like, be mindful of the relationship between aesthetics and function.

Is the design, function and structure relational to the front, top and bottom of the work? Is it well proportioned and balanced?

Consider...

Is the glass tempered? Glass should be tempered when necessary – some cook/baking ware, when used for tabletops and in cabinetry.

 

Is the glassware being used to hold or serve consumable purposes? Ensure the glass item is properly polished and smooth to touch, ensuring it will not harm its users.

 

 

Know what Health Standards should apply by becoming familiar with the Hazardous Products Act.

...Ask the Artist About

The Material

Glass is the earliest known synthetic material, made up of sand (silica), lime and soda ash. When combined with intense heat, these three components melt together to form glass. 

 

Glass in a hot molten state can be stretched, folded, twisted, blown and formed into a variety of shapes and sizes. Layers of glass can also be heated and fused together without becoming molten.

 

Glass can be transparent, translucent or opaque. It can be clear or coloured, either in the glass itself or with surface application of enamel, powder, or metal leaf or foil.

Glass

SWEETS

Identifying Features:

Glass pieces can be transparent or translucent depending what polishing techniques have been applied to the surface. They can be tinted or coloured a variety of different colours and shades to achieve a desired aesthetic/design. Depending on the thickness of the glass, a single piece can be different shades of a single colour. For example, a bottle can appear clear in its body, while the spout and base have a blue or green tint due to the multiple layers of glass required for stability.

 

Properties:

There are many different types of glass, each one tailored to its purpose or use. Safety (tempered) glass is used in windows and windshields because it crumbles instead of shattering when broken. Pyrex glass is used to make kitchenware that must be durable and withstand extreme temperatures, like casserole dishes and measuring cups. Artists and craftspeople use glass that is best suited to malleability, ease of annealing (more about that below) and range of colour. These types of glass are usually called studio glass or art glass.

 

Common Uses:

Glass is used to make a variety of things found in your daily life. In terms of craft, glass is used for lamps, beads, ornaments, paperweights, figurines, sculpture, jewellery and kitchenware. While providing aesthetic value and intrigue through its elegance and transparency, glass can form objects that range from completely functional to highly decorative.

 
 
SWEETS

Techniques

The techniques of craft glass exist in two stages: making and coldworking.

 

Making:

 

The most common techniques of making are glassblowing, fusing and lampworking (also called flameworking).

 

Glassblowing: In glassblowing, clear molten glass (over 2000 degrees F) is collected from a furnace onto the end of a long steel rod called a blowpipe. The maker blows down the pipe and traps the air in the glass bubble, then shapes the glass with a variety of tools. To prevent the glass from becoming too cool and stiff, it is heated back up regularly in a large cylinder called a glory hole.

 

The maker adds colour in the form of a solid rod, frit (crushed glass) or powder. Depending on the size and complexity of the object being made, this shaping process can take from a few minutes to many hours. Decorative elements like enamel or metal leaf or foil can also be added at this stage.

 

Once the piece is complete, it goes into a very hot annealing kiln, where it is cooled down slowly over many hours. Annealing allows stress to be released from the glass, making it more durable and less prone to cracking and breaking.

 

Lampworking: Lampworking (also called flameworking) takes place at a table-mounted torch that typically uses a combination of oxygen and either propane or natural gas. The maker can use rods of soda-lime glass (also called soft glass, although it’s very hard before it melts in the torch) or borosilicate glass to make beads, jewellery items, small sculptures, and figurines. The maker uses various areas of the torch flame to alternately melt and stabilize the object they are making. Lampworkers also use glass frit and powder, enamels, and metal leaf and foil. The tools used in lampworking are often smaller-scale versions of the ones used in glassblowing. Lampworked pieces can take from a few minutes to over an hour to create.

 

Once the piece is complete, it goes into a very hot annealing kiln, where it is cooled down slowly over many hours. Annealing allows stress to be released from the glass, making it more durable and less prone to cracking and breaking.

 

 

Fusing: In fusing, the maker starts with cold glass, cut into sheets of various colours. The sheets are typically 3-6 mm thick. The maker layers shapes of different coloured glass together then places them in a cold kiln. The kiln heats the glass to the point where the layers fuse together as one, but before the glass becomes molten. The kiln then cools back down to room temperature.

 

The maker sets the fused (flat) piece on top of a mould and returns it to the kiln. This time the kiln temperature is set high enough that the fused piece slumps into the mould, taking the shape of a bowl, or serving dish, or another item. The kiln then cools back down again.

 

Coldworking:

 

Regardless of the techniques used to create the glass piece, the maker may choose to work it further when it’s cold. A tile saw can slice through a glass piece to remove segments, for example giving a round vase an angular lip. A belt sander or grinder can remove undesirable “bits” protruding from the piece. A lathe can give a piece a wide range of surface effects, including faceting. Sandblasting can produce a frosted look on the surface of a piece or can carve a design deeply into the glass.

 

 
For Your Reference

Blowpipe: The hollow steel rod used in glass blowing to gather up hot molten glass from the furnace.

 

Cane: A rod of glass.

 

Cut Glass: the result of using grinding stones that are worked wet to cut designs onto glass.

 

Decorating: The glass vessel can be decorated with the addition of glass enamels, lustres, metal plating or through the removal of material such as through sandblasting and etching.

 

Direct Carving: Glass is carved, ground, chiselled or otherwise shaped like other sculptural materials.

 

Enamelled Glass: Opaque glass colours (glass powders) are melted onto the glass surface.

 

Engraving: Designs are cut or scratched onto the glass with a diamond point, stone, metal or copper wheel. The designs are normally more complex than cut glass work.

 

Etching: Glass can be etched by hydrofluoric acid.

 

Gather: A ball of molten glass taken from a pot or furnace on the end of a hollow blow rod.

 

Gilded: Metals, for example, gold, are fired onto glass.

 

Glory Hole: A high-temperature chamber used for reshaping glass either on a punty rod or blow pipe.

 

Iridized Glass: This when glass is chemically treated so its surface has a rainbow or iridescent appearance.

 

Kiln Firing: Firing glass in a kiln at a range of high temperatures produces fused glass. Depending on the temperature, firing in a kiln can produce slumping at low temperatures (595-677°C), tack fusing at medium temperatures (677-732°C) or a full fuse at high temperatures (732-816°C). All or some of these firing techniques can be applied to the same piece of glass, each having a different effect on depth and shape.

 

Leaded Glass: Refers to stain glass windows which are held together by lead cames.

 

Marver: The flat surfaces (graphite or steel) upon which glass is rolled to centre, shape or flatten any decoration that has been applied.

 

Punty Rod: A metal rod that is used to transfer and hold glass only when working with a glory hole.

 

Sandblasting: High-pressure air mixed with sand is applied to the surface of glass to carve a texture.

 

Shaping: Gravity and specialised tools aid with shaping, such as simply rotating the heated glass at select speeds and consistencies. The cooled piece of glass can still be shaped by grinding and polishing its surface.

 

Slumping: A shaping technique where items are made in a kiln by slumping the glass over moulds at high temperatures and letting gravity form the glass around said mould. This is a common technique with plates or serving dishes when only a shallow serving bed is needed.

 

Tempered Glass: Safety glass processed by controlled thermal or chemical treatments to increase its strength and durability compared to ‘normal’ glass. For example, if broken, tempered glass crumbles into small granular, less dangerous chunks, whereas untampered glass will break into sharp, jagged shards that pose a greater risk of injury to the user.

Thermal Shock: Refers to glass breakage that is caused by rapid or uneven heating or cooling.