(a) Rubber made by vulcanization is a artificial material.

(b) Man-made materials are made by processing natural materials.

(c) Nylon thread was developed simultaneously in New York and London.

(d) Rayon is also known as synthetic silk.

• Man continuously strives for newer and newer things. Increasing population, deforestation and limited natural resources are some of the reasons due to which the need for man-made materials arise.  
• Man tried to make different, usable artificial substances, from the natural substances.
• The production of low cost and plentiful materials satisfy man’s need.
• Another reason which led to the increase in the use of man-made material was to get a comfortable lifestyle.

Vulcanization is the process carried out for the production of hard rubber. In this process, raw rubber is heated with a mixture of sulphur and an appropriate additive, for three to four hours. This process makes rubber hard. Sulphur is added to give toughness to rubber.

Natural materials obtained from plants and animals are used to obtain fibers. The natural materials used to obtain fibres are cotton, jute, hemp, wool, silk, etc.

a. Soil- Soil is used for farming and agriculture, It is also used in construction, pottery, medicine and cosmetics.

b. Wood- It is used in making furniture, as a source of fuel, utensils, hand tools, musical instruments, wooden toys etc.

c. Nylon- It is used in making canopies of parachutes, tents, sleeping bags, sails, rope, tennis strings, fishing nets and clothes, etc.

d. Paper- It is used in making bags, envelopes, notebooks, packaging purpose etc.

e. Rubber- Rubber is used to make Balloons, erasers, rubber toys, rubber balls, tyres of all vehicles etc.

Paper is manufactured by the following process:

• For making paper, the pine like coniferous trees are felled.
• Logs of wood are made to pass through a debarker, where the barks of the tree are separated.

• Then the wood is chopped into small pieces and is mixed with some chemicals and water in digetser for the formation of the pulp.

• When the chemical process is completed, the fibres from the wood are separated.

• The obtained pulp is washed refined and sometimes even bleached.
• The pulp is made to travel down the screen to remove excess of water and then to the rollers where it is being dried and squeezed between large rollers to form rolls of paper. 

• It is then dried and then wound on the reels.

We must use cotton clothes in summers because they protect us from the heat of the sun. Cotton clothes are made from natural fibres. The sweat is absorbed in these fibres. The skin remains dry and the chance of catching skin infection is less. By using clothes made from synthetic fibres, we may feel uncomfortable. Therefore, we must use cotton clothes in summer.

• We must observe economy in the use of materials because they directly or indirectly affect our environment.
• Most of the natural materials which we obtain from our environment are exhaustible/non renewable resources i.e. once these resources are finished they cannot be renewed again or even if they can, it would take several years to do so.
• The man made materials which we use are largely non-biodegradable. Many times these man-made substances are hazardous for the environment. e.g. thermocol, plastic etc.
• Increased use of man-made materials pose a threat to the environment because their disposal is not easy and leads to environmental pollution.
• These examples state the importance of judicious use of both natural and man-made materials.

We very well know that paper is obtained from trees. Trees are important resources because they not only provide us with wood or paper but are also a habitat for various organisms.

• To obtain paper, more and more trees are felled.
• By excessive use of paper, large scale deforestation takes place.
• If trees and forests vanish, we have to face dangers such as climate change.

Therefore, saving paper is the need of the hour.

Man-made materials have more demand because of their characteristics like easy to use, low cost of production, cheaper products and variety of things which can be made from them.

• The original natural materials are changed into man-made material to suit our convenience. e.g. instead of cotton and wool fibres, synthetic fibres are more convenient for use.
• Plastic and thermocol are the materials that has fast replaced the natural alternatives.

Thus man-made material has more demand.

Humus is a natural material because its formation is a natural process. There are soil microbes that bring about decomposition process in the soil. From the dead and decaying remains of animals and plants humus is formed by them. This is a natural process and therefore humus is called a natural material.

Lac is a natural resin and is a product of animal origin. It is secreted by an insect, known as lac-insect. In order to obtain lac, these insects are cultured and the technique is called lac-culture. From the body of female lac insect this resinous substance is given out as secretion. When this substance comes in contact with air, it solidifies and forms lac. This lac is then collected and used for making jewellery etc.

Pearls are precious jewels and the only gems created by a living animal. They are formed when a microscopic foreign object finds its way inside a mussel or oyster.

Pearls are formed inside the shells of a bivalve marine animal. If any foreign particle enters the body of this animal, a layer of protective substance called chancre is deposited around it. This deposition ultimately forms pearl.

In the laboratories, artificially a bead is inserted in the body of an animal called Pearl oyster. Pearl oyster deposits layers of chancre around this bead. This is how cultured pearl is prepared.