The most widely used tin packaging, it is light and has a high thermal conductivity. Tin containers of the required dimensions can be made at canning factories. However, tin packaging has a number of disadvantages.

When canned food is stored in tinplate containers, corrosion processes occur, i.e., the transition of the metal under the influence of the environment (air or food products) into various oxide compounds or salts of organic acids.

The outer surface of a can when stored in warehouses, especially unheated ones, begins to become covered with oxidation products (rust). This process takes place despite the tin layer covering the iron base of the tin, because the tin layer has pores. Usually, when hot-tin coated, tin has 6-10 or more pores per square centimeter. Each point is a microelement where corrosion processes take place under the influence of moisture. In autumn, spring, and for the south and in winter, during the day in warehouses, the air temperature changes dramatically and, with its high relative humidity, conditions are created when air saturated with water vapor cools when it comes into contact with stacks of canned food (the temperature of canned food does not change as sharply as air ), near the surface of the tin container, it becomes supersaturated with water vapor and drops of moisture are deposited on the tin surface. In drops of moisture that have settled on the contaminated surface of the tin, an electric element iron-tin is formed, and the conductor is water contaminated with organic and inorganic compounds. Iron and tin have different electrical potentials. Under these conditions, iron dissolves, while tin is preserved. The water dries up, and the tin becomes covered with rusty spots.

When in contact with canned food products containing organic acids, the electrical potential of tin changes depending on the pH of the canning medium, and the transition of tin to canned food begins. For this reason, health authorities have rationed the tin content of canned foods. The maximum content of tin in vegetables and other types of canned food should not exceed 200 mg per 1 kg. Coating with varnish or enamel on the inner surface of the cans significantly reduces the transfer of tin into canned food.

In addition to hot-tinned tinplate, canning factories use white rolled tinplate without varnish and varnished grades ZhKL (hot-tinned lacquered can) and EZhKL (electrolytic tinned can lacquered) for the manufacture of cans and lids for glass containers. Rolled lacquered tinplate should have a shiny surface without lacquer drips, bubbles, unlacquered spots. The surface color of the tin should be uniform. The tinplate is available in various widths to reduce waste when making cans.

To reduce the consumption of tin, electrolytic (non-hot) tinned rolled tin is produced. The consumption of tin during electrolytic tinning is reduced by 2-3 times. Electrolytic tin plate is coated with a double layer of varnish.

In addition to tinplate, rolled tinplate of the ZhChKL brand (black lacquered canning tinplate) is produced, from which lids for glass containers are produced.

A number of works were carried out on the use of aluminum for the manufacture of canning containers and lids. Aluminum molds well. Any violations of the surface of aluminum during stamping are not as important as in tin, because the oxide film in places of violation under the influence of oxygen, air is quickly restored. Aluminum surface lacquering provides additional protection against corrosion. Aluminum corrosion products are white and are not regulated by health authorities. But when using aluminum, there are also a number of difficulties: aluminum cannot be soldered, so it is impossible to make prefabricated cans from it, it has a lower mechanical strength compared to tin, therefore, the rejection of cans increases during their manufacture and during loading and unloading operations. Aluminum has a reduced corrosion resistance to the acid environment of canned food, therefore, despite the varnishing of the inner surface of the cans, it is suitable only for packaging canned food with a pH of about 7 (meat, fish in oil, natural vegetables).

To combat corrosion, tinplate or other materials from which cans are made must be varnished. Varnishes and enamels used to cover tin should not contain harmful impurities: salts of heavy metals, substances that give the product an extraneous taste, smell or color.

Lacquer and enamel films must withstand mechanical and heat treatment, which is necessary for the manufacture of cans and technological processes. The film should not flake off the surface of the tin, form cracks, but it should withstand heat without change during sterilization for 2 hours. at a temperature of 100 ° or 1.5 hours at a temperature of 121 °.

The density and strength of the lacquer film is checked by boiling samples of varnished sheet metal for 2 hours. in 50% sugar solution, 3% common salt, 12% tomato puree and 3% acetic acid. Lacquer coatings must not be altered by this treatment.

The tin from which containers for canned food containing a lot of protein substances (crab, chicken) are made is coated with protein-resistant enamels.

Enamel must withstand two hours of boiling in a 3% sodium chloride solution or in a solution of 3% gelatin and 1% sodium chloride. The solution is saturated with hydrogen sulfide (H 2 S).

The composition of varnishes includes natural or synthetic organic resins (copal, etc.), oils (tung, linseed) and solvents (turpentine, spirit).

Protein-resistant enamel is made from varnish with the addition of zinc oxide (ZnO). This is necessary because during the sterilization process, protein compounds begin to break down under the influence of temperature, and in the process of decomposition, sulfur compounds are released, which, reacting with tin tin, give deposits on the surface of the tin (black-blue color) tin sulphide (SnS). If these protein breakdown products come into contact with an enamel film that contains zinc oxide, then white zinc sulfide (ZnS) compounds will form on the surface of the film, and not black-brown deposits (SnS).

Rotary machines are used to apply varnishes and enamels on tin. A special mass is applied to the shafts of the machine, which includes gelatin. After coating, the tin sheet enters the furnace. The varnish is annealed at a temperature of 180-220°. During annealing, the solvent evaporates from the varnish and the oil polymerizes. The film is made hard, elastic and insoluble in canning products.

To obtain good coatings (non-porous), the varnish is applied in two layers. The thickness of the coatings is 10-15 microns. The outer side of the can is sometimes lithographed. They apply drawings, printing, paints on special machines. In recent years, canneries have been equipped with machines capable of lithographic printing in four colors. A jar, the inner surface of which is varnished, and the outer surface with lithography and varnish, is much less exposed to corrosion.

According to the manufacturing method, tin cans are divided into prefabricated and seamless. The main type is a prefabricated cylindrical tin can (Fig. 3); it consists of three parts: body, bottom and cover. The body of the can is made from a blank (blank) having a longitudinal seam. The bottom and lid are connected to the body with a double seam. The longitudinal seam is made into a lock inside the can and soldered outside.

On the left - the ends of cans: 1 - with a bent flange; 2 - with a rounded flange; on the right - a double seaming seam: 1 - before the rollers work; 2 - after the first operation; 3 - after the second operation.

The end parts of the longitudinal seam are overlapped. If the longitudinal seam along the entire height is made into a lock, then when it is connected to the lid and bottom, so many layers of tin will be obtained (eleven instead of seven) that the tightness of the seam cannot be achieved.

The bottoms and lids have reliefs that create the elasticity of the jar, so the shape of the jar, after its increase due to the volumetric expansion of the products during the sterilization process, is restored upon cooling.

Whole-stamped cans do not have a seam. They are obtained by stamping on a special press (the body of the jar and the lid are stamped).

Characteristics of prefabricated cans are given in table. 6.

Bank number	Bank volume, cm 3	Can diameter, mm		Bank height, mm
		interior	outer	internal	outdoor

Mass production of cans is carried out on automatic lines, the productivity of which is very high - up to 300 cans per minute. On fig. 4 shows a diagram of an automatic tin can line.

1 and 1a - feeders; 2 - curly scissors; 3 - presses; 4 - pasting machines; 5 - disk shears; 6 - body-forming machine; 7, 10, 13, 16 - elevators; 8, 11, 14, 17 - heat; 9 - flange bending machine (flange); 12 - seaming machine; 15 - testing machine (tester).

According to the scheme, tin sheets are laid on the receiving platform of the automatic feeder, the sheets are fed by the feeder to the curly shears, where they are cut with a curly knife into curly strips. The use of a shaped knife reduces the waste of tin in the production of cans.

The cut strips are stacked in piles in the receiving part of the automatic presses. Two presses are installed in the line, on which bottoms and lids for cans are stamped from figured strips. They flow through the estrus to the curling disc, which curls the lids or bottoms (ends) and stacks them in piles. Subsequently, the stacks of ends are transferred to pasting machines. Two machines are installed in the line, which apply rubber paste to the ends. The pasting machine has a dryer in which the paste is dried and only the rubber base remains at the ends. After the pasting machine, the dried ends are transferred and placed in the receivers of the seaming machines. This completes the production of ends for cans.

The machines carry out the body of the can, soldering it, connecting it to the bottom and checking the finished can; machines work in the following order.

The feeder feeds sheets to double disc shears, on which the sheet is cut into rectangles according to the dimensions (blanks) necessary for the manufacture of the can body. These rectangular strips of tin are called blanks in factory practice. The latter are manually stacked in piles in the receiving part of the body-forming machine, where the body is molded, a longitudinal seam is formed, it is riveted and soldered with solder (40% tin and 60% lead). The soldered finished body of the can is lifted up by the elevator and sent along the chute to the flange-bending machine (flange), where the body is bent on both sides, i.e., it is prepared for connection with the bottom and the lid. The beaded bodies are transported by an elevator and a chute to a seaming machine. Previously, it was indicated that bottoms are placed in the seamer shop. After seaming, the manufactured cans are fed by the elevator through the chute to the testing machine, which is called in factory practice testor. The test is carried out with compressed air. If the can is sealed, then the air pressure in it does not change during the test period; if the can is not sealed, the pressure drops, and the machine rejects such a can. The cans that have passed the test are sent to the elevator and by chute to the packaging warehouse.

With the advent of household can seamers, we all have the opportunity to cook stew, canned fish and other homemade preparations in cans. Of course, for this we still need an autoclave.

Types of cans

Few people use cans for canning, so people's ideas about them are very superficial. Let's try to fill this gap. We will not go into much depth, we will focus only on the main points.

So, what types of cans are there?

By design, tin cans can be divided into seamless and composite. In seamless cans, the bottom and side surface are a single whole, they are drawn from a single sheet of tin (hence the name). Only the cover rolls up. As a rule, seamless cans are cans of small height. Composite cans have three parts: a bottom, a side surface (body) and a lid. The bottom is the same lid that is rolled to the side surface at the can manufacturer. Moreover, as a bottom, at the request of the customer, both a standard lid and an Easy Open lid (easy to open) can be rolled on.

Composite cans, in turn, can be divided into welded and brazed. The side surface (body) of composite cans is made from a sheet of tin, which is bent into a cylinder, and then welded or sealed. Visually welded cans have a neat, beautiful weld. The solder seam is not so even, often with solder influxes. All modern manufacturers of cans make only welded cans. Soldered is an outdated technology. In Western countries, they are recognized as harmful and dangerous for food products, and are prohibited from production. There is no such ban in our country, therefore, when you go to any store, you can see canned food in such jars. All this is a legacy of the Soviet period: at large canning enterprises, lines for the production of brazed cans have been preserved since those times.

According to their design features, tin cans can still be divided into smooth and zig-zag (with ribs). The higher the bank, the more often zigovka is used on its lateral surface to give greater rigidity.

And, perhaps, the last constructive feature is the type of bottom: straight or narrowed. Banks with a narrowed bottom appeared much later. They are very convenient in terms of storage and transportation of finished canned products.

Now it's time to talk about the geometric dimensions of cans. Tin cans have their own GOSTs, for example GOST 5981-88. In accordance with GOST, each jar is assigned a number, for example, No. 9, No. 46, and also indicates the diameter, height, volume and other parameters. The most commonly used cans of the following diameters: 72.8 mm (cans No. 22, No. 4, No. 7, No. 9, No. 46) 83.4 mm (cans No. 5, No. 6, No. 38), 99 mm (cans No. 2, No. 3, No. 12, No. 13). This is the inside diameter. The outer diameter of the can is always slightly larger. It happens that they indicate: bank No. 9 72.8 mm or bank No. 9 76 mm. No need to think that these are different cans, just different diameters are indicated: internal and external, respectively. For cans of different diameters, when seaming, you need your own equipment for seaming machines. This should be taken into account when purchasing seaming equipment. The height of the can in this case does not play a role.

And in conclusion, a few words about covers. As already mentioned, there are standard lids and Easy Open lids that open easily without using an opener. To seam these caps, you also need your own equipment for seaming machine. In addition, Easy Open covers from different manufacturers differ in geometry (of course, there are the same ones), and each of them needs its own equipment. Therefore, if you plan to use Easy Open lids, you must first decide on the supplier of these lids, and only then buy a can seamer.

Since ancient times, people have faced the question - how to save food from spoilage? Over time, the problem became more global. Food had to be learned to preserve in large volumes (for expeditions and armies).

The very first canned food made by man was discovered during excavations of the tomb of Pharaoh Tutankhamen in Egypt. Products were in the depths of the earth for about 3000 years. They were ducks roasted and embalmed with olive oil in a clay bowl, the parts of which were held together with a resinous substance. These canned foods have withstood the test of millennia and were even good for food (there is evidence that these ducks were good for animal feed). Many of the modern ones can envy these canned goods.

Mark Porcius Cato the Elder (Roman senator) was one of the first "canners". In his work “On Agriculture” there was a note: “If you want to have grape juice all year round, then pour it into an amphora, grind the cork and lower the amphora into the pool. Take it out after 30 days. The juice will stand for a whole year ... "

In the year 63 of the 18th century, Lomonosov, organizing an expedition to explore the polar regions and the Northern Sea Route, made an order: "Making dried soup with spices and without spices, one and a half pounds of each variety." That is, 200 years ago, the soup concentrate traveled across Russia by land and the Arctic Ocean right to Kamchatka.

In 1795, about to take over all of Europe, Napoleon Bonaparte announced that a cook who could find a way to keep food fit for a long time would be paid 12,000 francs.

Disagreements between two scientists, Needham and Spallanzani (the first insisted that microbes appear from inanimate matter, and the second said that all microbes have their progenitors) led, completely far from science as such, French culinary specialist Nicolas Francois Appert to idea - products, hermetically packed and subjected to heat treatment, can be stored for a long time. Apper turned out to be right, and his products prepared in a special way, having experienced long-term storage, were recognized as high-quality.

Upper spent 10 years proving the well-known fact today that the contents of jars filled with jam or soup do not deteriorate and remain good for a year if they are tightly corked and boiled in water for a long time. His invention was immediately put on stream for the warring French army.

Apper was rewarded for his invention with a state prize in 1809 and awarded the title "Benefactor of Mankind". He later opened his own business. The store was called "Miscellaneous food in bottles and boxes." There, Apper sold hermetically sealed ones made by him. The store had a small factory for the production of canned food. After that, Upper wrote the book "The Art of Preserving Plant and Animal Substances for a Long Period".

Scientific confirmation of Apper's ideas came only after 60 years. In 1857, at a meeting of the Society of Naturalists, Louis Pasteur, then an unknown scientist, made a work that there are microbes in the world that cause the processes of rotting products. To maintain the life of these microbes, certain conditions are needed - the level of temperature, high humidity, the presence of oxygen and, the most basic condition, the absence of antibiotic substances in the product. If these conditions are violated, the microbes will die. It is on this principle that the methods of preserving products are based - sterilization and pasteurization.

Although the Frenchman was the first to discover the method of long-term storage, another person, the Englishman Peter Durand, brought him to mind. Peter Durand patented tin cans, the familiar canned food that was much more convenient to use than glass bottles. Of course, they were very different from modern ones. The production was done by hand, besides, the jars had an inconvenient lid. Since 1826, England supplied the army with its own canned meat. But in order to open such banks, the rank and file were forced to use a hammer and chisel.
However, the palm in the production of canned food was taken not by France and England, but by the USA, where production began on the creation of machines designed for the manufacture of various cans.
Since 1819, in America they began to produce canned products from lobster, tuna, they also began to preserve fruits. It was here that tin cans acquired the form that we see to this day. Everything went very well. Canned food was in great demand, and they were literally swept off the shelves. Well, in 1860 a knife for these cans was invented. Again in the USA.

In the Russian state, of course, they knew about the innovation of the French. In 1821, the St. Petersburg and Moscow public debated animatedly about an extract from the Russian Archive magazine. It said that the turtle soup, which was poured into cans, was safely brought from the East Indies to the shops in London. However, despite this, the first canned food factory appeared only in 1870. The main customer, of course, was the army. Produced canned food in St. Petersburg. There were 5 types of them: fried beef, stew, porridge, meat with peas and pea soup.

On the 200th anniversary of the invention of the tin can, the Japan Canning Society has produced a unique batch of canned food. They reliably repeat those canned food that Napoleonic soldiers ate. In particular, the Japanese made again 5 varieties of canned food according to the recipes of Apper himself. In particular, the Japanese made a soldier's consommé, vegetable stew, pot-au-fee soup, melange of beans with champignons and a strawberry dessert. They were ceremonially opened and eaten at the headquarters of the Tokyo Canning Society.

Today's canned food, which is the diet of astronauts on the orbital station, of course, differs from the old army rations. Today they are unlikely to remember the Frenchman Apper, opening another tube of food, but the importance of canned food in our lives will not decrease from this.

What are cans made from? and got the best answer

Answer from Marshall Mathers[guru]

Answer from ***SKARLETT***[guru]
from tin

Answer from Smallv!lle[guru]
Made of tinplate, often covered with a special varnish. "Tinplate" - coated on both sides with layers of tin (electrolytically)

Answer from winny[guru]
made of thin tinned steel - tinplate

Answer from Lidiya Bolshakova[guru]

made of thin tinned steel (canning sheet)
Tinning is the application of a thin layer of tin to the surface of metal products. Tinning is carried out to protect the metal from corrosion or to prepare for soldering (the tinned surface is better wetted with solder).
Steel (from German Stahl) is a deformable (ductile) alloy of iron with carbon (and other elements), characterized by a eutectoid transformation. The carbon content in steel is not more than 2.14%, but not less than 0.022%. [source not specified 156 days] Carbon gives iron alloys strength and hardness, reducing ductility and toughness.
The production process of a tin can includes the following operations:
Rolls of tin or aluminum tape are brought to the plant.
The tape is covered with an oil film and passed through a drawing press, which forms shallow bowls without a bottom. At the same time, bottoms and lids are “cut out” on another machine.
At the next stage, the walls of the bowls are pulled out and thinned. They take the form of a tin can.
The edge trimming machine removes unevenness and shortens the jar to the desired height.
A coating is applied to the walls of the jar, which will become the basis for the pattern. After drying in a hot oven, the image is applied to the jars and varnished.
The blanks are sent to the shop for filling cans.
Banks are connected to the bottoms, filled with a product or drink and closed with lids. The device is able to "serve" up to 2 thousand cans per minute.
Ready canned food is passed through the detector. If the filling rate is not met, the product is rejected.

“Tin has outlived its “bronze age” and has become the metal of a tin can” - this is a quote from Academician A.E. Fersman’s excellent essay on tin, from the book “Entertaining Geochemistry”. The title of the essay follows the title of this chapter.

Indeed, known to man since ancient times, tin has been used for thousands of years as the main additive to copper. The great alloy - bronze - was obtained as a result of this union.

But the Bronze Age has passed. Bronzes have become one of the widely used, but by no means the main alloys. And tin has found other uses. It made friends with iron, more precisely, with tin, thin sheets of rolled iron. Thousands of applications has such a sheet. And one of the most important is to be a container of a canned product, in other words, a tin can.

Tin has a significant resistance to chemical attack. It does not react with water, it dissolves very slowly in dilute acids, only when heated to 150 degrees does it begin to oxidize with atmospheric oxygen. All this fully satisfies the high requirements that can be made to the metal that covers the inside of the tin of a can that comes into contact with food intended for humans. That is why tin covers the inner surface of cans.

There are several ways to carry out such a coating of tin with tin. The hot method has long been known, when a cleaned and degreased product is immersed through a layer of flux into molten tin. The extracted product is already covered with semi-dry.

In case it is necessary to polish one side of the metal sheet, it is cleaned, heated from below and the cleaned side is rubbed with tin and flux. This is done with an ordinary dry and clean rag.

Nowadays, however, these methods of tinning are a thing of the past. Today, tin cans are tinned in galvanic baths.

World tin production is subject to rather sharp fluctuations. So, in 1940, about 250 thousand tons of this metal were mined in the capitalist countries, and in 1952 - only about 170 thousand tons. Perhaps there is no country in the world in which tin would not be considered a scarce metal. And most of this tin goes everywhere to the production of tinplate - the metal of cans.

The lack of tin makes it work in three directions. Geologists are trying to find new deposits of tin stone - tin ores.

Metallurgists are looking for ways to replace tin in alloys, to do without it. And everyone should think about how to save the already mined tin, not to let it die.

Each tin is about half a gram of tin, which can be returned to the production cycle if the tin gets into the scrap, and does not rust under the fence. Extracting tin from old cans is not difficult: after all, tin dissolves in alkalis. Old cans are immersed in them, and then the tin is isolated by electrolysis.

The second very serious item of tin consumption is alloys. After all, this metal is part of bronzes, low-melting alloys, printing alloys, bearing materials. But especially a lot of it goes to the production of solders.

And here are the passport properties of this metal. It melts at 232 degrees, boils at 2430 degrees. Its specific gravity under normal conditions is about 7.3 g per cubic meter. see. Tin is soft, it can be scratched with a fingernail. Easily forged and rolled into the thinnest foil.

There was a time when not only spoons and bowls were made of tin, but also buttons for soldiers. They say that in one harsh winter, these buttons suddenly “sick”. More recently, shiny, durable, they were covered with a grayish coating for no reason and crumbled into dust. It seemed that the tin of the buttons had fallen ill with some contagious disease. They even came up with a name for this phenomenon - "tin plague".

And everything was explained very simply. The fact is that the usual tin known to us is stable only at temperatures above minus 13 degrees. Below this temperature, tin recrystallizes, it greatly increases in volume and therefore begins to crumble into dust. This process is especially fast at a temperature of about minus 30 degrees. Apparently, such a temperature was standing when the buttons of the soldiers' overcoats began to crumble.

Such is the service of the tin man. Although this metal is not the immediate neighbor of copper in the periodic table, I have placed it in this chapter. For too many centuries it has been in a fire-bonded friendship with copper, and its present service to man is too similar to the work of zinc to be able to tear this metal away from its friends and work colleagues.

Copper is the chosen one of electricity.

save metal

The production of non-ferrous metals - we have already seen this in a number of examples - is a complex, expensive, labor-intensive process. Remember: to get one ton of copper, you need to extract 100 tons of ore; to get one ton of nickel, it is necessary to raise 200 tons of ore from the bowels of the earth, and even 300 tons of tin. How much human labor is spent on this! And how it is necessary to save this labor embodied in metal!

Once upon a time, all the non-ferrous metal mined was spent only on the production of weapons, tools and household items. Hot copper, gold-like brass, sonorous bronze were also used to make jewelry. The cabins and superstructures of warships were hung with coppers, which the sailors had to fiercely scrub. Bulky and heavy chandeliers, various candlesticks, ventilation grilles, faucets, etc. were made from the same materials. Yes, technology did not know a hundred years ago, for example, other materials for the manufacture of all these and many other items.

It is a completely different time - a time when old materials are being replaced by new ones, such as aluminum, plastic and refined wood. And for non-ferrous metals, new important applications are found in those places where no one can replace them at all.

The heart of an electric motor is where the copper should be, not in an ornate doorknob or heavy as a mortar candlestick.

No, there is no place for precious tin and copper in a bulky bronze ink device!

We must try to keep the pewter items out of the cold. They may die irrevocably.

Why spend precious nickel, which is part of stainless steel, for finishing railway and tram cars, river and marine vessels?

But, of course, when revising the norms for the consumption of non-ferrous metals, reducing the list of products for which non-ferrous metal is used, we must not allow the quality of products to suffer because of this. Replacement should be made only where it is really expedient.

Non-ferrous metals should be saved not only by replacing them with other materials.

Saving non-ferrous metals is the reduction of machining allowances, and the careful collection and sorting of metal chips, and the fight against waste during remelting and heat treatment, and reducing the weight of the corresponding parts.

At many enterprises producing cast iron alloyed with magnesium, not magnesium scrap and waste are used for this purpose, but primary magnesium.

Very often products, the excellent quality of which would be ensured by a thin coating with an anti-corrosion layer, are entirely made of expensive stainless alloys.

Saving non-ferrous metals is both the collection of non-ferrous metal scrap and the collection of household waste.

Each used tin can is no longer the tin that the consumer needs.

Remelting a ton of aluminum scrap requires incomparably less expenditure than producing a ton of primary aluminum.

Protect non-ferrous metal! Spend it only where it is really irreplaceable! - with such an appeal addressed to our people the Central Committee of the Communist Party of the Soviet Union in December 1959.

This call met with the liveliest response of the entire Soviet people.