![Empty tin can2009-01-19](https://upload.wikimedia.org/wikipedia/commons/a/a8/Empty_tin_can2009-01-19.jpg)
A steel can, tin can, tin (especially in
British English
British English (BrE, en-GB, or BE) is, according to Lexico, Oxford Dictionaries, "English language, English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in ...
,
Australian English
Australian English (AusE, AusEng, AuE, AuEng, en-AU) is the set of varieties of the English language native to Australia. It is the country's common language and ''de facto'' national language; while Australia has no official language, Engli ...
,
Canadian English
Canadian English (CanE, CE, en-CA) encompasses the varieties of English native to Canada. According to the 2016 census, English was the first language of 19.4 million Canadians or 58.1% of the total population; the remainder spoke French ( ...
and South African English),
steel packaging, or can is a
container
A container is any receptacle or enclosure for holding a product used in storage, packaging, and transportation, including shipping.
Things kept inside of a container are protected on several sides by being inside of its structure. The term ...
for the distribution or storage of goods, made of thin metal. Many cans require opening by cutting the "end" open; others have removable covers. They can store a broad variety of contents: food, beverages, oil, chemicals, etc.
Steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
cans are made of
tinplate
Tinplate consists of sheets of steel coated with a thin layer of tin to impede rusting. Before the advent of cheap milled steel, the backing metal was wrought iron. While once more widely used, the primary use of tinplate now is the manufacture ...
(tin-coated steel) or of tin-free steel. In some dialects, even
aluminium cans are called "tin cans".
Steel cans are
highly recyclable, unlike materials like
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
, with around 65% of steel cans being recycled.
History
The tin canning process was conceived by the Frenchman
Philippe de Girard
Philippe Henri de Girard (February 1, 1775 – August 26, 1845aged 70) was a French engineer and inventor of the first flax spinning frame in 1810, and the person after whom the town of Żyrardów in Poland was named. He was also the uncredited i ...
, who got a British merchant
Peter Durand
Peter Durand (21 October 1766 – 23 July 1822) was an English merchant who is widely credited with receiving the first patent for the idea of preserving food using tin cans. The patent (No 3372) was granted on August 25, 1810, by King George II ...
to patent the idea in 1810. The canning concept was based on experimental
food preservation
Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit ...
work in glass containers the year before by the French inventor
Nicholas Appert
Nicolas Appert (17 November 1749 – 1 June 1841) was the French inventor of airtight food preservation. Appert, known as the "List of persons considered father or mother of a field, father of Food Science", was a confectioner. Appert described ...
. Durand did not pursue food canning, but, in 1812, sold his patent to two Englishmen,
Bryan Donkin
Bryan Donkin FRS FRAS
(22 March 1768 – 27 February 1855) developed the first paper making machine and created the world's first commercial canning factory. These were the basis for large industries that continue to flourish today. Bryan D ...
and
John Hall John Hall may refer to:
Academics
* John Hall (NYU President) (fl. c. 1890), American academic
* John A. Hall (born 1949), sociology professor at McGill University, Montreal
* John F. Hall (born 1951), professor of classics at Brigham Young Unive ...
, who refined the process and product, and set up the world's first commercial canning factory on Southwark Park Road, London. By 1813 they were producing their first tin canned goods for the
Royal Navy
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
. By 1820, tin canisters or cans were being used for gunpowder, seeds, and turpentine.
Early tin cans were sealed by
soldering
Soldering (; ) is a process in which two or more items are joined by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involv ...
with a tin–
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
alloy, which could lead to
lead poisoning.
In 1901 in the United States, the
American Can Company
The American Can Company was a manufacturer of tin cans. It was a member of the Tin Can Trust, that controlled a "large percentage of business in the United States in tin cans, containers, and packages of tin." American Can Company ranked 97th amon ...
was founded, at the time producing 90% of United States tin cans.
Canned food in tin cans was already quite popular in various countries when technological advancements in the 1920s lowered the cost of the cans even further.
In 1935, the first beer in metal cans was sold; it was an instant sales success.
Description
Most cans are
right circular cylinders with identical and parallel
round
Round or rounds may refer to:
Mathematics and science
* The contour of a closed curve or surface with no sharp corners, such as an ellipse, circle, rounded rectangle, cant, or sphere
* Rounding, the shortening of a number to reduce the number ...
tops and bottoms with
vertical sides. However, cans for small volumes or particularly-shaped contents, the top and bottom may be rounded-corner rectangles or ovals. Other contents may suit a can that is somewhat conical in shape.
Fabrication of most cans results in at least one ''rim''—a narrow ring slightly larger than the outside diameter of the rest of the can. The flat surfaces of rimmed cans are recessed from the edge of any rim (toward the middle of the can) by about the width of the rim; the inside diameter of a rim, adjacent to this recessed surface, is slightly smaller than the inside diameter of the rest of the can.
Three-piece can construction results in top and bottom rims. In two-piece construction, one piece is a flat top and the other a
deep-drawn cup-shaped piece that combines the (at least roughly) cylindrical wall and the round base. Transition between wall and base is usually gradual. Such cans have a single rim at the top. Some cans have a separate cover that slides onto the top or is hinged.
Two piece steel cans can be made by "drawing" to form the bottom and sides and adding an "end" at the top: these do not have side seams. Cans can be fabricated with separate slip-on, or
friction fit covers and with covers attached by hinges. Various easy opening methods are available.
In the mid-20th century, a few milk products were packaged in nearly rimless cans, reflecting different construction; in this case, one flat surface had a hole (for filling the nearly complete can) that was sealed after filling with a quickly solidifying drop of molten
solder
Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...
. Concern arose that the milk contained unsafe levels of lead leached from this solder plug.
Advantages of steel cans
A number of factors make steel cans ideal containers for beverages. Steel cans are stronger than cartons or plastic, and less fragile than glass, protecting the product in transit and preventing leakage or spillage, while also reducing the need for secondary packaging.
Steel and aluminium packaging offer 100% barrier protection against light, water and air, and metal cans without resealable closures are among the most tamper-evident of all packaging materials.
Steel cans preserve and protect the product from damage by light, oxidation, extremes of temperature and contamination, safeguarding flavour, appearance and quality from factory to final consumer. Food and drink packed in steel cans has equivalent vitamin content to freshly prepared, without needing preserving agents.
Steel cans also extend the product's shelf-life, allowing longer sell-by and use-by dates and reducing waste.
As an ambient packaging medium, steel cans do not require cooling in the supply chain, simplifying logistics and storage, and saving energy and cost.
At the same time, steel's relatively high thermal conductivity means canned drinks chill much more rapidly and easily than those in glass or plastic bottles.
A World Steel Association initiative, Choose Steel, is encouraging the use of steel for beverage cans.
File:Fransk Linolja - 2021.jpg, A can of French linseed oil.
File:Canned-air.jpg, Compressed gas with dispensing valve
File:Trevqrp.png, Flip-top can with hinged cover
File:Ronsonol Lighter Fluid.JPG, Can of lighter fluid
File:Yellow oil can.JPG, Special can for dispensing oil
File:Camp fuel.jpg, Camp stove fuel in "F-Style" can
File:Alkydharzlack.jpg, Paint can with double friction cover (plug)
File:Assorted biscuits Khong Guan.JPG, Can with slip on cover
File:Boite de cirage Baranne ouverte.jpg, Can of shoe polish
Shoe polish (or boot polish) is a waxy paste, cream, or liquid that is used to polish, shine, and waterproof leather shoes or boots to extend the footwear's life and restore its appearance. Shoe polishes are distinguished by their textures, ...
File:Ridgways Assam Tea tin pic3.JPG, Tea tin
Materials
No cans currently in wide use are composed primarily or wholly of tin; that term rather reflects the nearly exclusive use in cans, until the second half of the 20th century, of
tinplate
Tinplate consists of sheets of steel coated with a thin layer of tin to impede rusting. Before the advent of cheap milled steel, the backing metal was wrought iron. While once more widely used, the primary use of tinplate now is the manufacture ...
steel
Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...
, which combined the physical strength and relatively low price of steel with the
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
resistance of tin. Depending on contents and available coatings, some canneries still use tin-free steel.
In some local dialects, any metal can, even aluminium, might be called a "tin can". Use of
aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
in cans began in 1957. Aluminium is less costly than tin-plated steel but offers the same resistance to corrosion in addition to greater
malleability
Ductility is a List of materials properties, mechanical property commonly described as a material's amenability to Drawing (manufacturing), drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a materia ...
, resulting in ease of manufacture; this gave rise to the two-piece can, where all but the top of the can is simply stamped out of a single piece of aluminium, rather than laboriously constructed from three pieces of steel.
A can traditionally has a printed
paper or plastic label glued to the outside of the curved surface, indicating its contents. Some labels contain additional information, such as recipes, on the reverse side. More recently labels are sometimes printed directly onto the metal before or after the metal sheet is formed into the individual cans.
In November 1991, US can manufacturers voluntarily eliminated
lead
Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
seams in food cans. However, imported food cans continued to include lead soldered seams.
In 1995, the US
FDA
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
issued a rule prohibiting lead soldered food cans, including both domestic and imported food cans.
In modern times, the majority of food cans in the UK have been lined with a plastic coating containing
bisphenol A
Bisphenol A (BPA) is a chemical compound primarily used in the manufacturing of various plastics. It is a colourless solid which is soluble in most common organic solvents, but has very poor solubility in water. BPA is produced on an industrial s ...
(BPA). The coating prevents acids and other substances from corroding the tin or aluminium of the can, but leaching of BPA into the can's contents was investigated as a potential health hazard.
Standard sizes
Cans come in a variety of shapes: two common ones are the "soup tin" and the "tuna tin". Walls are often stiffened with rib bulges, especially on larger cans, to help the can resist dents that can cause seams to split.
Can sizes in the United States have an assortment of designations and sizes. For example, size 7/8 contains one serving of half a
cup
A cup is an open-top used to hold hot or cold liquids for pouring or drinking; while mainly used for drinking, it also can be used to store solids for pouring (e.g., sugar, flour, grains, salt). Cups may be made of glass, metal, china, clay, ...
with an estimated weight of 4
ounce
The ounce () is any of several different units of mass, weight or volume and is derived almost unchanged from the , an Ancient Roman units of measurement, Ancient Roman unit of measurement.
The #International avoirdupois ounce, avoirdupois ounce ...
s; size 1 "picnic" has two or three servings totalling one and a quarter cups with an estimated weight of 10 ounces; size 303 has four servings totalling 2 cups weighing 15 ounces; and size 10 cans, most widely used by food services selling to cafeterias and restaurants, have twenty-five servings totalling 13 cups with an estimated weight of 103 ounces (size of a roughly 3
pound coffee
Coffee is a drink prepared from roasted coffee beans. Darkly colored, bitter, and slightly acidic, coffee has a stimulant, stimulating effect on humans, primarily due to its caffeine content. It is the most popular hot drink in the world.
S ...
can). These are U.S. customary cups (not British Imperial standard).
In the United States,
cook book
A cookbook or cookery book is a kitchen reference containing recipes.
Cookbooks may be general, or may specialize in a particular cuisine or category of food.
Recipes in cookbooks are organized in various ways: by course (appetizer, first cou ...
s sometimes reference cans by size. The Can Manufacturers Institute defines these sizes, expressing them in three-digit numbers, as measured in whole and sixteenths of an inch for the container's nominal outside dimensions: a 307 × 512 would thus measure 3 and 7/16" in diameter by 5 and 3/4" (12/16") in height. Older can numbers are often expressed as single digits, their contents being calculated for room-temperature water as approximately eleven ounces (#1 "picnic" can), twenty ounces (#2), thirty-two ounces (#3) fifty-eight ounces (#5) and one-hundred-ten ounces (#10 "coffee" can).
In parts of the world using the
metric system
The metric system is a system of measurement that succeeded the Decimal, decimalised system based on the metre that had been introduced in French Revolution, France in the 1790s. The historical development of these systems culminated in the d ...
, tins are made in 250, 500, 750
ml (
millilitre
The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: â„“) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3) ...
) and 1 L (
litre
The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: â„“) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3). ...
) sizes (250 ml is approximately 1 cup or 8 ounces). Cans imported from the USA often have odd sizes such as 3.8 L (1
US gallon
The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use:
*the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austral ...
), 1.9 L (1/2 US gallon), and 946 ml (2
US pint
The pint (, ; symbol pt, sometimes abbreviated as ''p'') is a unit of volume or capacity in both the imperial and United States customary measurement systems. In both of those systems it is traditionally one eighth of a gallon. The British impe ...
s / 1
quart
The quart (symbol: qt) is an English unit of volume equal to a quarter gallon. Three kinds of quarts are currently used: the liquid quart and dry quart of the US customary system and the of the British imperial system. All are roughly equ ...
).
In the UK and Australia, cans are usually measured by net weight. A standard size tin can holds roughly 400 g; though the weight can vary between 385 g and 425 g depending on the density of the contents. The smaller half sized can holds roughly 200 g, typically varying between 170 g and 225 g.
Fabrication of cans
Rimmed three-piece can construction involves several stages;
* Forming a tube and welding or soldering the seam of the sides
* Joining the bottom end to the tube
* Printing or attaching labels to the can
* Filling the can with content; sterilization or retorting is required for many food products
* Joining the wall and top "end".
Double seam
A double seam is a canning process for sealing a tin can by mechanically interlocking the can body and a can end (or lid).
Originally, the can end was soldered or welded onto the can body after the can was filled. However, this introduced a va ...
rims are crucial to the joining of the wall to a top or bottom surface. An extremely tight fit between the pieces must be accomplished to prevent leakage; the process of accomplishing this radically deforms the rims of the parts. Part of the tube that forms the wall is bent, almost at its end, turning outward through 90 degrees, and then bent further, toward the middle of the tube, until it is parallel to the rest of the tube, a total bend of 180 degrees.
The outer edge of the flat piece is bent against this toward the middle of the tubular wall, until parallel with the wall, turning inward through 90 degrees. The edge of bent portion is bent further through another 90 degrees, inward now toward the axis of the tube and parallel to the main portion of the flat piece, making a total bend of 180 degrees. It is bent far enough inward that its circular edge is now slightly ''smaller'' in diameter than the edge of the tube. Bending it yet further, until it is parallel with the tube's axis, gives it a total bend of 270 degrees. It now envelops the outward rim of the tube.
Looking outward from the axis of the tube, the first surface is the unbent portion of the tube. Slightly further out is a narrow portion of the top, including its edge. The outward-bent portion of the tube, including its edge, is still slightly further out. Furthest out is the 90-degree-bent portion of the flat surface.
The combined interacting forces, as the portion of the flat surface adjacent to the interior of the tube is indented toward the middle of the tube and then outward ''forward'' the axis of the tube, and the other bent portions of the flat piece and the tube are all forced ''toward'' the axis of the tube, drives these five thicknesses of metal against each other from inside and out, forming a "dry" joint so tight that welding or solder is not needed to strengthen or seal it. Illustrations of this process can be found on pages 20–22 of the FAO Fisheries Technical Paper 285 "Manual on fish canning" locate
here
File:Inside of a tin platted can.jpg, Inside of a tin can.
Design and manufacture
Steel for can making
The majority of steel used in packaging is tinplate, which is steel that has been coated with a thin layer of tin, whose functionality is required for the production process.
The tin layer is usually applied by electroplating.
Two-piece steel can design
Most steel beverage cans are two-piece designs, made from 1) a disc re-formed into a cylinder with an integral end, double-seamed after filling and 2) a loose end to close it.
Steel cans are made in many different diameters and volumes, with opening mechanisms that vary from ring pulls and tab openers, to wide open mouths. Modern can making lines may produce up to 1000 cans per minute.
Drawn-and-ironed (DWI) steel cans
The process of re-forming sheet metal without changing its thickness is known as 'drawing'. Thinning the walls of a two-piece can by passing it through circular dies is called 'ironing'. Steel beverage cans are therefore generally referred to as drawn-and-ironed, or DWI, cans (sometimes D&I). The DWI process is used for making cans where the height is greater than the diameter, and is particularly suited to making large volumes of cans of the same basic specification.
Steel can wall thicknesses are now 30% thinner and weigh 40% less than 30 years ago, reducing the amounts of raw materials and energy required to make them. They are also up to 40% thinner than aluminium.
Magnetic properties
Steel is a ferrous metal and is therefore
magnetic. For beverage packaging this is unique. This allows the use of magnetic conveyor systems to transfer empty cans through the filling and packing processes, increasing accuracy and reducing potential spillage and waste. In
recycling
Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...
facilities, steel cans may be readily separated from other waste using magnetic equipment including cross-belt separators, also known as overband magnets, and drum magnets.
Opening cans
The first cans were heavy-weight containers that required ingenuity to open, with implements such as knives. Not until several years later, after can manufacturers started using thinner metal sheets, were any dedicated
can opener
A can opener (in North American English and Australian English) or tin opener (used in British English) is a mechanical device used to open tin cans (metal cans). Although preservation of food using tin cans had been practiced since at leas ...
s developed.
While
beverage can
A drink can (or beverage can) is a metal container designed to hold a fixed portion of liquid such as carbonated soft drinks, alcoholic drinks, fruit juices, teas, herbal teas, energy drinks, etc. Drink cans are made of aluminum (75% of ...
s or cans of fluid such as
broth
Broth, also known as bouillon (), is a savory liquid made of water in which meat, fish or vegetables have been simmered for a short period of time. It can be eaten alone, but it is most commonly used to prepare other dishes, such as soups, ...
can merely be punctured to remove the product, solid or semisolid contents require removing one end of the can. This can be accomplished with a heavy knife or other sharp tool—but
can openers are much more convenient.
Some cans, such as those used for
sardine
"Sardine" and "pilchard" are common names for various species of small, oily forage fish in the herring family Clupeidae. The term "sardine" was first used in English during the early 15th century, a folk etymology says it comes from the It ...
s, have a specially scored lid so that the user can break out the metal by the leverage of winding it around a slotted
church key
A church key or churchkey is an American term for various kinds of bottle openers and can openers.
Etymology
The term in the beverage-opening sense
A sense is a biological system used by an organism for sensation, the process of gath ...
. Until the mid-20th century, some sardine tins had solder-attached lids, and the winding key worked by forcing the solder joint apart.
The advent of
pull tabs in beverage cans spread to the canning of various food products, such as
pet food
Pet food is animal feed intended for consumption by pets. Typically sold in pet stores and supermarkets, it is usually specific to the type of animal, such as dog food or cat food. Most meat used for animals is a byproduct of the human food ind ...
or
nuts (and non-food products such as
motor oil and
tennis ball
A tennis ball is a ball designed for the sport of tennis. Tennis balls are fluorescent yellow in organised competitions, but in recreational play can be virtually any color. Tennis balls are covered in a fibrous felt which modifies their aerodyna ...
s). The ends are known as ''easy open'' lids because they open without any tools or implements. An additional innovation developed for specifically for food cans uses a tab that is bent slightly upwards, creating a larger surface area for easier finger access.
Cans can be made with easy open features. Some cans have
screw cap A screw cap or closure is a common type of closure for bottles, jars, and tubes.
Usage
A screw closure is a mechanical device which is screwed on and off of a "finish" on a container. Either continuous threads or lugs are used. It must be engi ...
s for pouring liquids and resealing. Some have hinged covers or slip-on covers for easy access. Paint cans often have a removable plug on the top for access and for reclosing.
File:Dosenoeffner.silber2.png, Mechanism of a can opener
A can opener (in North American English and Australian English) or tin opener (used in British English) is a mechanical device used to open tin cans (metal cans). Although preservation of food using tin cans had been practiced since at leas ...
File:Euroshopper canned marrowfat peas.jpg, Can that requires a can opener
File:Tomato soup in a can pull open top.jpg, Soup can with a ring-pull tab
File:Can(Easy Open Can).JPG, Opened can with a ring-pull tab
File:Corned-beef-1.jpg, Keyed side opening
File:Sardines in a can.jpg, Easy open sardine can
File:POE Stay-on tab.jpg, Stay-on tab
Recycling and re-use
Steel from cans and other sources is the most
recycled packaging material.
Around 65% of steel cans are recycled.
In the United States, 63% of steel cans are recycled, compared to 52% of aluminium cans. In Europe, the recycling rate in 2016 is 79.5%.
Most can recycling occurs at the smelters, but individual consumers also directly reuse cans in various ways. For instance some people use two tin cans to form a
camp or survival stove to cook small meals.
Sustainability and recycling of steel beverage cans
Steel recycling
From an ecological perspective, steel may be regarded as a closed-loop material: post-consumer waste can be collected, recycled and used to make new cans or other products. Each tonne of scrap steel recycled saves 1.5 tonnes of CO
2, 1.4 tonnes of iron ore and 740 kg of coal. Steel is the world's most recycled material, with more than 85% of all the world's steel products being recycled at the end of their life: an estimated 630 million tonnes of steel scrap were recycled in 2017, saving 945 million tonnes of CO
2.
Steel can recycling
A steel can can be recycled again and again without loss of quality, however for the food grade steel it's required to remove a
tin
Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal.
Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...
from the scrap metal, which is done by way of
electrochemistry
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...
: the tin is leached from a high pH solution at low negative voltage.
Recycling a single can saves the equivalent power for one laundry load, 1 hour of TV or 24 hours of lighting (10W LED bulb).
Steel beverage cans are recycled by being melted down in an electric arc furnace or basic oxygen furnace.
Most steel cans also carry some form of recycling identification such as the Metal Recycles Forever Mark Recyclable Steel and the Choose Steel campaign logo.
There is also a campaign in Europe called Every Can Counts, encouraging can recycling in the workplace
Smaller carbon footprint
All beverage packaging creates CO
2 emissions at every stage in the production process, from raw material extraction, processing and manufacture through to recycling. However, steel cans are an ecological top performer, as cans can always be recycled. The steel industry needs the used cans and will use them in the production of new steel product. By recycling the cans and closing the loop, CO
2 emissions are dramatically reduced. There is also the potential for higher global steel recycling rates as consumers become more aware of the benefits.
Health issues
Dissolution of tin into the food
Tin is corrosion resistant, but acidic food like fruits and vegetables can corrode the tin layer. Nausea, vomiting, and diarrhea have been reported after ingesting canned food containing 200 mg/kg of tin.
A 2002 study showed that 99.5% of 1200 tested cans contained below the UK regulatory limit of 200 mg/kg of tin, an improvement over most previous studies largely attributed to the increased use of fully lacquered cans for acidic foods, and concluded that the results do not raise any long term food safety concerns for consumers. The two non-compliant products were voluntarily recalled.
Evidence of tin impurities can be indicated by color, as in the case of pears, but lack of color change does not guarantee that a food is not tainted with tin.
Bisphenol-A
![Bisphenol A](https://upload.wikimedia.org/wikipedia/commons/e/ee/Bisphenol_A.svg)
Bisphenol-A (BPA) is a controversial chemical compound present in commercially available tin can plastic linings
and transferred to canned food. The inside of the can is coated with an
epoxy
Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also coll ...
coating, in an attempt to prevent food or beverage from coming into contact with the metal. The longer food is in a can, and the warmer and more acidic it is, the more BPA leaches into it. In September 2010, Canada became the first country to declare BPA a toxic substance.
In the
European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
and Canada, BPA use is banned in baby bottles.
The FDA does not regulate BPA (see
BPA controversy#Public health regulatory history in the United States). Several companies, like
Campbell's Soup
Campbell Soup Company, doing business as Campbell's, is an American processed food and snack company. The company is most closely associated with its flagship canned soup products; however, through mergers and acquisitions, it has grown to becom ...
, announced plans to eliminate BPA from the linings of their cans,
but have not said which chemical they plan to replace it with. (See
BPA controversy#Chemical manufacturers reactions to bans.)
See also
*
Albion metal
*
Drink can
A drink can (or beverage can) is a metal container designed to hold a fixed portion of liquid such as carbonated soft drinks, alcoholic drinks, fruit juices, teas, herbal teas, energy drinks, etc. Drink cans are made of aluminum (75% of ...
*
Oil can
*
Tin box
A tin box is a tinplate container. Tinplate metal is primarily steel with a very thin tin coating. Tin-free steel is also used. In some cultures, these boxes or cans are referred to as "tin boxes" or sometimes even "tins". Many “tin boxes†...
*
Tin can wall
A tin can wall is a wall constructed from tin cans, which are not a common building source. The cans can be laid in concrete, stacked vertically on top of each other, and crushed or cut and flattened to be used as shingles. They can also be us ...
References
General references, further reading
Nicolas AppertGuide to Tinplateon
About.com
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* Yam, K. L., ''Encyclopedia of Packaging Technology'', John Wiley & Sons, 2009,
* Soroka, W, ''Fundamentals of Packaging Technology'', Institute of Packaging Professionals (IoPP), 2002,
External links
Steeluniversity Packaging ModuleSteel industry fact sheet on food cans
{{DEFAULTSORT:Steel and tin cans
Containers
Packaging
Food storage containers
British inventions
1810 introductions
Food packaging
Steel
19th-century inventions
Metallic objects