Tag Archives: Manufacturing

How silk is made from cocoon?

Silk is one of the most favorite fabric materials in the world. It has been so for thousands of years. The soft and shiny material is almost a prized item in many places. Silk has been known for several millenniums. The earliest known specimen of silk fabric was discovered from China, which dates back to 3630 BC. China is also the largest producer of the material. The historical Silk Route says how much importance silk had in bygone eras.
Silk is essentially a natural protein fiber. It is made by several insect larvae to form cocoons. However, the industrial silk is produced from the worms of moth species Bombyx mori. An unfortunate side effect of this is that the pupae have to be killed to obtain the material. It takes the killing of about 3000 caterpillars to get a pound of silk.

Silk cocoon from silk worm (probably Bombyx mori)
The cultivation of silkworms is called sericulture. The eggs of moths are incubated for 10 days. They hatch to produce caterpillars which are fed on mulberry leaves for about five weeks. The caterpillars then begin to spin the cocoon. This time, they would weigh about 10,000 times heavier than they did at the time of hatching. While making cocoons, the caterpillars move in a certain pattern. They secrete a liquid protein named fibroin from two glands and force it out through openings in head called spinnerets. They are coated in a protective agent called sericin, which hardens with air contact. The caterpillar would produce about 1 mile of filament in three days.
The cocoons are then soaked in boiling water to kill the pupae and soften the sericin. The fibers are then unwound to form a continuous thread. This process is called reeling. Since a single strand is too thin for commercial use, a few (usually between 3 and 10) are twisted together to form a single silk thread. This is called reeled silk. There are different twisting methods, and each produces a distinct type of silk. The shining appearance of silk is from the triangular prism-like structure of the fiber. Owing to the structure, the incoming light refract at different angles, thereby producing different colors.
Since numerous pupae have to be killed to produce silk, many animal right movements have raised their voice against the industry. The scientific world is trying to come up with methods that don’t require killing of the worms, which may come to fruition soon.

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How does a fuel-air bomb work? How does it differ from a conventional bomb?

Fuel-air bomb
Most bombs consist of a metal case filled with explosives like TNT or RDX and a means of detonating the contents. By contrast, a fuel-air bomb is filled with a highly combustible fuel in either liquid or gel form. The fuel may be as exotic as aluminum powder or as simple as petrol. Detonating this device is like lighting a match in a gas-filled room. A small charge in front of the bomb or warhead releases fuel, which mixes with the air to form vapor cloud. Immediately thereafter, a detonator at the rear of the bomb triggers the midair explosion over the target as shown in the image above.
The United States used fuel-air bombs in Vietnam War to obliterate the targeted jungle area and clear away mines and booby traps. When used against mass troops and enemy fortification, such bombs would simply liquidate them with both a fireball and concussion. They would burst eardrums, rapture internal organs and collapse the lungs of troops further away. It’s not without justification that these explosive devices are often called a poor man’s atomic bombs, though the blast and the shock they produce is still only a fraction of that of a tactical nuclear weapon. However, they do have one advantage: there is no radiation in fuel-air bomb.
Here’s a Discovery Channel video (from YouTube) of fuel-air explosive. Note that HBA is not affiliated with creators of this video.

Additional reading:
Fuel-air explosive (Wikipedia)

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What is the difference between cluster bomb and conventional bomb?

Cluster bombs are also classified as conventional bombs insofar as they are not nuclear bombs. There are, however, many kinds of conventional bombs, including armor-piercing, fragmentation and incendiary bombs. Among these, the cluster type is a particularly vicious weapon if used against massed troops.
Each bomb usually contains hundreds of bomblets. After the bomb is dropped, it rotates along the horizontal axis. (See the diagram given above.) A small explosive charge opens the casing, and the centrifugal force of the spinning bomb distributes the bomblets far and wide. When dropped properly from the optimum altitude, the cluster bomb will kill anyone within an area of about 5,300 square meters. The bomblets themselves are often pre-fragmented so as to split them into dozens of sharpnels. Obviously, they cause particular harm to human targets.

Additional reading:
Cluster munition (Wikipedia)

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What are Polarized sunglasses? How do they work?

Edwin H. Land
Before we answer these questions it will be necessary to explain what Polarized sunglasses do. As you know, ordinary light travels in waves, or vibrations. When the waves hit a smooth surface, such as a mirror, a pool of water, a wall or even the leaves of trees, they behave like a handful of flat skipping-stones thrown across a pond. Those that happen to strike the surface edge-on will plunge in, those that strike the surface with their flat sides do not plunge in, but I skip off. The light waves that skip off are the ones that make up most of the dazzling glare you see on a bright day. Since most glare surfaces are horizontal, these glare waves strike at your eyes with their vibrations running side to side rather than up and down. Polarized sunglasses have lenses of a special plastic that can block these side to side vibrations. Think of two boys, one on either side of a picket fence, each holding the end of a jumping rope passed between two pickets. The boys can make the rope go up and down in a wave-like motion; but they cannot give it a circular motion as for jumping rope. Polarized material acts somewhat like picket fence. In the sunglasses, the Polarized lenses are set with their ‘pickets’ vertical. They permit light vibrations that are moving crosswise.
There are certain natural substances that will polarize light. A mineral called Iceland spar is one ot them; tourmaline is another. Researchers have tried for a long time to find or invent a polarizing material that would be available on a large scale, for polarized light has many uses in industry and in optics. Shortly after 1925 an American scientist, Edwin H. Land, (photo, above) brought out a plastic polarizing sheet that he called Polarized film. In the plastic were tiny polarizing crystals. Later polarizers invented by Land have no crystals. Instead, their molecules are lined up in such a way that they polarize light.
Sometimes even light that has passed through a Polarized lens is much too bright for comfort. Polarized sunglasses with double lenses, or discs, reduce the light as much as you wish. One disc rotates. You may set it so that the two discs polarize the light in the same direction, or you may turn it so that they partly cancel each other. You can even block off all the light. (To go back to your picket fence, you could set a second fence crosswise, behind the upright fence. Now your rope could not move freely in any direction). Perhaps you have ridden in a train that has Polarized windows. They have double panes that can be adjusted, like the need shades, for you can block out a little, or all, of the light by turning one of the discs. Perhaps someday all our automobiles will have their headlights and windshields made of Polarized glass. This would block off glare and make driving far safer and more comfortable.

Additional reading:
Sunglasses (Wikipedia)

Why an automobile’s windscreen glass shatters into rounded pieces when it breaks?

It is because this particular type of glass has undergone the process of toughening or lamination. Automobile windscreen and aircraft windshields must withstand severe impacts without shattering. The kind of special glass used for such purposes is called safety glass. It is far stronger than ordinary glass and does not shatter into sharp, dangerous splinters.
Two main kinds of safety glass are produced—toughened and laminated glass. Toughened glass is made by  heating glass sheet in a furnace. It has its temperature uniformly raised until it is just beginning to become plastic. It is then quickly lifted out of the furnace, bent where necessary between matching tools and then cooled rapidly and uniformly all over by jets of cold air blown forcibly on to it. This process is called tempering. When toughened glass breaks, it shatters into hundreds of blunt, rounded particles which cannot cause bad cuts. 
Laminated glass is a kind of glass and plastic sandwich. Two sheets of flat glass with a layer of polyvinyl butyral in between are gently heated under vacuum which evacuates all air from the laminates and is then heated to bonding temperature under pressure. Laminated glass is safe because when it breaks the pieces of glass stick to the sandwiched layer of plastic.

Additional reading:
Toughened glass (Wikipedia)
Laminated glass (Wikipedia)

How are bombs made out of chemical fertilizers?

If media reports are to be believed, terrorists make some of their bombs out of chemical fertilizer. Do they really? How? One wonders.
Forget the ‘how’ part of the question, since bomb-making is the last thing one would risk to describe at length. Only the underlying principle can be summerised in a few words. The major ingredient of fertilizer is ammonium nitrate. It is somewhat unstable chemical that would degrade violently with a bit of encouragement. In fact, nitric acid which is needed to make explosive like TNT (trinitrotoluene) is derived from oxidised ammonia. Many fertilizer bombs made by terrorists also contain extra sources of carbohydrates to help stoke up the explosive power of the fertilizer, In addition, diesel is used, besides phosphorus compounds that react to simple friction. Packing all these materials into a container that will compress them on impact can create enough friction to cause the phosphorus to ignite. Alternatively, a detonating spark can be generated with battery linked to a timer device.

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How is colorful striped toothpaste manufactured?

Manufacturers give colorful stripes to toothpaste by using a two-in-one like tube within a tube. The main tube is filled with white paste. Another tube within the main tube is filled with colored paste. This type of design prevents white and colored pastes from mixing. A few holes are made on the upper part of the colored paste tube so that when the tube is pressed colored paste also comes out through these holes forming colorful stripes.
Some manufacturers also use two different but non-mixing pastes in a single tube. But this method does not give accurate result.

More Reading:
Toothpaste (Wikipedia)

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Why photochromic glasses turn dark when exposed to sunlight?

The lenses of photochromic spectacles are made of glass mixed with minute crystals of light sensitive silver iodide or bromide. These crystals are so minute that they have length of only 50 angstrom (1 angstrom = 0.0000000001 meter). As these crystals split and scatter in sunlight the transparent lenses automatically start becoming somewhat dark. Eyes are not dazzled because some of the sunrays are obstructed by these crystals. The crystals remain embedded in the lenses. Unlike a liquid when strained flows out of the strainer the photochromic glass does not allow these scattered crystals to flow out. As soon as direct exposure to sunlight is withdrawn the crystals of silver iodide or bromide fuse together and the lenses become transparent again.

Photochromic glasses were invented by a chemist named Dr. R.H. Dalon and were first manufactured in 1964 by American company named Corning.

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What ingredients are used for making ink for ball pen and fountain pen?

Ink is made from two main constituents, viz. color pigment and liquid which can carry color pigment via the nib. These constituents of ink are made from various substances. In some countries manufacturers use tincture of a wood known as logwood (such logwood trees grow profusely in Central America, Mexico and the West Indies). Natural color of logwood is deep red but after long exposure to open air this wood automatically becomes blue-black. The pigment of this color for making ink is extracted through distillation. It is essential that color of ink remains fast on paper and does not become blurred.

In order to infuse this property in ink manufacturers besides mixing 3.5 grams pigment in each liter of distilled water add 5.0 grams golic acid, 7.5 grams ferrous sulphate and 1.0 gram tartaric acid. The ink of ball pen has to be viscous rather than liquid and should not evaporate like liquid. Therefore, a colorless viscous substance named ethylene glycol is used in manufacture of ball pen ink instead of distilled water. The line drawn by tiny bearing of ball pen is very thin. It does not spread automatically on paper so it does not become bold. To overcome this drawback about 20 times more pigment is used in making ball pen ink as compared with the ink for pen.

The reason for a hole in the nib of a fountain pen is quite elementary and can be gauged with some focused reasoning. Just as tiny ball bearing performs basic work of writing in case of ball pen, split nib performs the work of writing by the pen. As the nib is placed on paper some light pressure that comes to be applied on it slightly widens the split of nib. This phenomenon brings internally stored ink via serrated feeders on to the split of nib through capillary action – and thus writing on paper commences. It is obvious that as the ink comes out it creates vacuum inside pen. The hole on the nib is the tiny window which lets in air to fill the vacuum, because writing can not proceed unless there is equilibrium between internal and external atmospheric pressures.

Additional reading:
Ballpoint pen (Wikipedia)
Fountain pen (Wikipedia)
Ink (Wikipedia)

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What is thermocol? And what is its manufacturing process?

Thermocol is a commercial name like Coca-Cola. In 1951 the researchers of a German company named BASF successfully restructured chemical bonding of polystyrene (a synthetic petroleum product) molecules and developed a substance named stretch polystyrene. This substance was named Thermocol, which nowadays is manufactured through a simple process. Thermoplastic granules are expanded through application of steam and air. Expanded granules become much larger in size but remain very light.
Thermocol is a good resister of cold and heat but since it is a petroleum product it dissolves in any solvent of petroleum.

Watch the video of the manufacturing process of thermocol. (HBA is not affiliated with the creators of the video.)

Additional reading:
Polystyrene (Wikipedia)

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