In pop-up or automatic toasters, bread slices are inserted vertically into the slots (generally only large enough to admit a single slice of bread each) on the top of the toaster. A lever on the side of the toaster is pressed, activating the toaster. 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 heating elements of a pop-up toaster are usually oriented vertically, parallel to the bread slice – although there are some variations.
In earlier days, the completion of the toasting operation was determined by a mechanical clockwork timer; the user could adjust the running time of the timer to determine the degree of “doneness” of the toast, but the first cycle produced less toasted toast than subsequent cycles because the toaster was not yet warmed up. Toasters made since the 1930s frequently use a thermal sensor, such as a bimetallic strip, located close to the toast. This allows the first cycle to run longer than subsequent cycles. The thermal device is also slightly responsive to the actual temperature of the toast itself. Like the timer, it can be adjusted by the user to determine the “doneness” of the toast.
The most commonly used methods to adjust heat supplied to the toast are either variable time or a heat sensor.
Among pop-up toasters, those toasting two slices of bread are more purchased than those which can toast four. 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. The marketing and price of toasters may not be an indication of quality for producing good toast. A typical modern two-slice pop-up toaster can draw from 600 to 1200 watts.
In 2012 in the United States, a typical market price for a pop-up toaster was US$15.
Toaster oven (Japan)
Toaster ovens are small electric ovens with a front door, wire rack and removable baking pan. To toast bread with a toaster oven, slices of bread are placed horizontally on the rack. When the toast is done, the toaster turns off, but in most cases the door must be opened manually. Most toaster ovens are significantly larger than toasters, but are capable of performing most of the functions of electric ovens, albeit on a much smaller scale. They can be used to cook toast with toppings, like garlic bread or cheese, though they tend to produce drier toast since their heating elements are located farther from the toast (to allow larger items to be cooked). They take 4–6 minutes to make toast as compared to 2–3 minutes in pop-up toasters. Since the toast lies on bars in a toaster oven, the toast will have untoasted stripes on one side. The evidence from product testing does not indicate that convection toaster ovens perform better than regular toaster ovens.
As an appliance, the space toaster ovens require on a countertop ranges from 16 by 8 inches (41 cm × 20 cm)to 20 by 10 inches (51 cm × 25 cm). In 2017 in the United States, a typical market price for a toaster oven was US$30-240.
A conveyor toaster can make several hundred pieces of toast in an hour
Conveyor toasters are designed to make many slices of toast and are generally used in the catering industry, in cafeterias, diners and institutional cooking facilities, as they are suitable for large-scale use. Bread is toasted at a rate of 300–1600 slices an hour, making conveyor toasters ideal for a large restaurant that is consistently busy. Such devices have occasionally been produced for home use as far back as 1938, when the Toast-O-Lator went into limited production.
Toaster before the use of electricity
Toaster with an Edison screw fitting, c. 1909
General Electric Model D-12 toaster, from 1910s
Before the development of the electric toaster, sliced bread was toasted by placing it in a metal frame or on a long-handled toasting-fork and holding it near a fire or over a kitchen grill. Utensils for toasting bread over open flames appeared in the early 19th century, including decorative implements made from wrought iron.
The first electric bread toaster was invented by Alan MacMasters in Edinburgh, Scotland in 1893.
Development of the heating element
The primary technical problem at the time was the development of a heating element which would be able to sustain repeated heating to red-hot temperatures without either 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 with the toaster.
Macmaster’s 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, mostly only 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.
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. One of the first applications the Hoskins company had considered for chromel was toasters, but eventually abandoned such efforts to focus on making just the wire itself.
The first commercially successful electric toaster was introduced by General Electric in 1909 for the GE model D-12.
Dual-side toasting and automated pop-up technologies
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 the toaster with automatic bread turner. The company also produced the “toaster that turns toast.” Before this, electric toasters cooked bread on one side and then it was flipped by hand to toast the other side. Copeman’s toaster turned the bread around without having to touch it.
The automatic pop-up toaster, which ejects the toast after toasting it, was first patented by Charles Strite in 1921. In 1925, using a redesigned version of Strite’s toaster, the Waters Genter Company introduced the Model 1-A-1 Toastmaster, 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.
Toasting technology after the 1940s
By the middle of the 20th century, some high-end U.S. toasters featured automatic toast lowering and raising, with no levers to operate — simply dropping the slices into the machine commenced the toasting procedure. A notable example was the Sunbeam T-20, T-35 and T-50 models (identical except for details such as control positioning) made from the late 1940s through the 1960s, which used the mechanically multiplied thermal expansion of the resistance wire in the center element assembly to lower the bread; the inserted slice of bread tripped a lever to switch on the power which immediately caused the heating element to begin expanding thus lowering the bread.
When the toast was done, as determined by a small bimetallic sensor actuated by the heat passing through the toast, the heaters were shut off and the pull-down mechanism returned to its room-temperature position, slowly raising the finished toast. This sensing of the heat passing through the toast, meant that regardless of the color of the bread (white or wholemeal) and the initial temperature of the bread (even frozen), the bread would always be toasted to the same degree. If a piece of toast was re-inserted into the toaster, it would be only reheated.
Newer additions to toaster technology include wider toasting slots for bagels and thick breads, the ability to toast frozen breads, and the option to heat a single side or slot. Most toasters can also be used to toast other foods such as teacakes, Pop Tarts, potato waffles and crumpets, though the addition of melted butter or sugar to the interior components of automatic electric toasters often contributes to eventual failure. In rare cases, some hobbyists modify toasters to print images and logos on bread slices.