HARD GLASS — A glass of high viscosity at elevated temperatures. Has a high softening point and is difficult to melt.
HIGH TEMPERATURE GLOVES — Safety gloves worn when hand are exposed to dangerous temperatures.
HIGH TEMPERATURE WIRE — The technical term for this would be High temperature wire. Rated at 2000' Fahrenheit. High-temperature wire is sometimes used for making connections in fused glass jewelry. This wire will hold up to fusing temperatures, but will fire scale a bit and turn almost gray.
HOT CASTING — A type of casting where molten glass is poured into a mold.
HOT GLASS — Working with or manipulating glass while it is in a molten condition.
HOT-FORMED, HOT-WORKED — The generic term for glass that is manipulated while it is hot.
HOT METAL MAN — Also called a Batch Man or Color Man, supervises the mixing of glass batches and formulates the recipes, which are often the hallmark of a glass company.
ICE GLASS – A decorative effect that causes the surface of the glass to resemble cracked ice, achieved by plunging the hot glass into cold water and withdrawing it quickly to create small fissures in the surface.
INCALMO — The technique of joining two or more sections of blown glass while hot. Italian decorative glassblowing technique.
INCLUSIONS — A collective term for bubbles, precious metal, glass particles, and other material that have been added to the internal layer of a glass object for decorative effect. Any object fused between two layers of glass.
INLAY — A decorative technique where a pattern is carved into clay at the leather hard stage and contrastingly colored clay is forced into the decoration. When the clay is a little drier the excess is scraped of to reveal the pattern.
INTAGLIO — A method of engraving whereby the design is cut into the object and lies below the surface plane. The German name for this technique is Tiefschnitt.
IRIDIZED — A type of multi-hued or rainbow colored finish which is achieved by spraying metal salts onto hot glass and then re-firing the piece. A surface treatment where a metallic oxide is bonded to the glass while the surface is hot. This causes the surface of glass to reflect a rainbow like color.
IRON OXIDE — Fe2O3 is a colorant, when combined with the right glaze and firing, iron oxide can produce greens, browns, blacks, yellows, oranges, subtle blues and grays. Iron is also a useful colorant in clay bodies and is introduced by adding high iron clays to the clay recipe.
JACKS — Large tong-like tools that are used to create score lines in the neck of a piece, among other things. It is the main tool used by glassblowers, and is also known as a borsella or pucellas.
JEWEL — A piece of glass that has been cut and faceted or press-molded into a geometric shape like a jewel. Often incorporated into leaded glass artwork.
JEWELRY BLANK — Jewelry that has a space to add a piece of fused glass.
JEWELRY FINDINGS — The hardware necessary for jewelry making.