A gel (coined by 19th-century Scottish chemist Thomas Graham, by clipping from gelatine) is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state. By weight, gels are mostly liquid, yet they behave like solids due to a three-dimensional cross-linked network within the liquid. It is the crosslinking within the fluid that give a gel its structure (hardness) and contribute to the adhesive stick (tack). In this way gels are a dispersion of molecules of a liquid within a solid in which the solid is the continuous phase and the liquid is the discontinuous phase.

Gel: Nonfluid colloidal network or polymer network that is expanded throughout its whole volume by a fluid.

Note 1: A gel has a finite, usually rather small, yield stress.

Note 2: A gel can contain:

Note 3: Corrected from ref., where the definition is via the property identified in Note 1 (above) rather than of the structural characteristics that describe a gel.

A color gel or color filter (British spelling: colour gel or colour filter), also known as lighting gel or simply gel, is a transparent colored material that is used in theater, event production, photography, videography and cinematography to color light and for color correction. Modern gels are thin sheets of polycarbonate or polyester, placed in front of a lighting fixture in the path of the beam.

Gels have a limited life, especially in saturated colors. The color will fade or even melt, depending upon the energy absorption of the color, and the sheet will have to be replaced. In permanent installations and some theatrical uses, colored glass filters or dichroic filters are being used. The main drawbacks are additional expense and a more limited selection.

History

Gelatin desserts are desserts made with sweetened and flavored gelatin.

They can be made by combining plain gelatin with other ingredients or by using a premixed blend of gelatin with additives. Fully prepared gelatin desserts are sold in a variety of forms, ranging from large decorative shapes to individual serving cups.

Regional names

Brands

Popular brands of premixed gelatin include:

History

Before gelatin became widely available as a commercial product, the most typical gelatin dessert was "calf's foot jelly". As the name indicates, this was made by extracting and purifying gelatin from the foot of a calf. This gelatin was then mixed with fruit juice and sugar.