Toaster

Glowing filaments of a modern 2-slice toaster

In pop-up or automatic toasters, a single vertical piece of bread is dropped into a slot on the top of the toaster. A lever on the side of the toaster is pressed down, lowering the bread into the toaster and activating the heating elements. The length of the toasting cycle (and therefore the degree of toasting) is adjustable via a lever, knob, or series of pushbuttons, and when an internal device determines that the toasting cycle is complete, the toaster turns off and the toast pops up out of the slots.

The completion of toasting may be determined by timer or by a thermal sensor, such as a bimetallic strip, located close to the toast.

Toasters may also be used to toast other foods such as teacakes, toaster pastry, potato waffles and crumpets, though resultant accumulation of fat and sugar inside the toaster can contribute to its eventual failure.

Among pop-up toasters, those toasting two slices of bread are more purchased than those which can toast four.[1] Pop-up toasters can have a range of appearances beyond just a square box, and may have an exterior finish of chrome, copper, brushed metal, or any color plastic.[1] The marketing and price of toasters may not be an indication of quality for producing good toast.[1] A typical modern two-slice pop-up toaster can draw from 600 to 1200 watts.[2]

Beyond the basic toasting function, some pop-up toasters offer additional features such as:

• One-sided toasting, which some people prefer when toasting bagels
• The ability to power the heat elements in only one of the toaster's several slots
• Slots of various depth, length, and width to accommodate a variety of bread types
• Provisions to allow the bread to be lifted higher than the normal raised position, so toast that has shifted during the toasting process can safely and easily be removed

A conveyor toaster

Conveyor toasters are designed to make many slices of toast and are generally used in the catering industry, restaurants, cafeterias, institutional cooking facilities, and other commercial food service situations where constant or high-volume toasting is required. Bread is toasted at a rate of 300–1600 slices an hour; the doneness control on such a toaster adjusts the conveyor speed, thus altering the time during which the bread is near the heat elements. Conveyor toasters have been produced for home use; in 1938, for example, the Toast-O-Lator went into limited production.[3]

The primary technical problem in toaster development at the turn of the 20th century was the development of a heating element which would be able to sustain repeated heating to red-hot temperatures without breaking or becoming too brittle. A similar technical challenge had recently been surmounted with the invention of the first successful incandescent lightbulbs by Joseph Swan and Thomas Edison. However, the light bulb took advantage of the presence of a vacuum, something that couldn't be used for the toaster.

Macmasters' toaster was commercialized by the Crompton, Stephen J. Cook & Company of the UK as a toasting appliance called the Eclipse. Early attempts at producing electrical appliances using iron wiring were unsuccessful, because the wiring was easily melted and a serious fire hazard. Meanwhile, electricity was not readily available, and when it was, it was usually only available at night.

The problem of the heating element was solved in 1905 by a young engineer named Albert Marsh, who designed an alloy of nickel and chromium, which came to be known as Nichrome.[8][9][10][11]

The first US patent application for an electric toaster was filed by George Schneider of the American Electrical Heater Company of Detroit in collaboration with Marsh.[9][12] One of the first applications that the Hoskins company had considered for its Chromel wire was for use in toasters, but the company eventually abandoned such efforts, to focus on making just the wire itself.[10]

The first commercially successful electric toaster was introduced by General Electric in 1909 for the GE model D-12.[9][13][14]

United States patent #1,394,450. "Bread-Toaster", patented 18 October 1921 by Charles Strite.

In 1913, Lloyd Groff Copeman and his wife Hazel Berger Copeman applied for various toaster patents, and in that same year, the Copeman Electric Stove Company introduced a toaster with an automatic bread turner.[15] Before this, electric toasters cooked bread on one side, meaning the bread needed to be flipped by hand in order to cook both sides. Copeman's toaster turned the bread around without having to touch it.[16]

The automatic pop-up toaster, which ejects the toast after toasting it, was first patented by Charles Strite in 1921.[17] In 1925, using a redesigned version of Strite's toaster, the Waters Genter Company introduced the Model 1-A-1 Toastmaster,[18] the first automatic, pop-up, household toaster that could brown bread on both sides simultaneously, set the heating element on a timer, and eject the toast when finished.

By the middle of the 20th century, some high-end U.S. toasters featured automatic toast lowering and raising, without the need to operate levers — simply dropping the bread into one of these "elevator toasters", such as the Sunbeam Radiant Control toaster models made from the late 1940s through the 1960s, begins the toasting cycle. These toasters use the mechanically multiplied thermal expansion of the resistance wire in the center element assembly to lower the bread; the inserted slice of bread trips a lever switch to activate the heating elements, and their thermal expansion is harnessed to lower the bread.

When the toast is done, as determined by a small bimetallic sensor actuated by the heat passing through the toast, the heaters are shut off and the pull-down mechanism returns to its room-temperature position, slowly raising the finished toast. This sensing of the heat passing through the toast means that regardless of the type of bread (white or whole grain) or its initial temperature (even frozen), the bread is always toasted to the same consistency.