Method : The master from which the copies will be taken is first prepared from a special non-absorbent glazed sheet of paper and special carbon paper which acts as the reproducing medium. This carbon paper is known as hectographed carbon and contains aniline based dye. These carbons are available in different colours, typically purple, red, green, black, blue, brown and yellow.
To construct a master the glazed surface of the master paper is placed in direct contact with the coated surface of the hectocarbon. The required information is then drawn, typed or written onto the surface of the master paper, causing a mirror image to be developed on the glazed side.
If a thermal copier is available it can also be used to prepare a hectographic master. This is a quicker and cleaner method.
Duplication
Once the master is ready it is attached to the drum of the duplicator with the carbon image outward. The copy paper is then fed into the machine. The function of the machine is to impregnate the copy paper with spirit in its passage through the machine so that it is moistened immediately before it comes into contact with the master on the drum. Since the contact of paper with master is brought about by a pressure wheel, the reaction of the spirit with the carbon causes an image to be transferred to duplicating paper.
Use
Mainly in educational establishments, that is class handouts.
Individual duplicating copies are relatively cheap to produce, the duplicator itself is simple and easily maintained.
Copy Quality
Poor - satisfactory
Colour
Multiple colours available simultaneously
Economic Run
Both carbon and master paper are cheaply available.
Master copy can be prepared easily.
The process is simple.
Good quality paper is used for copies.
Many colours can be duplicated simultaneously.
Disadvantages
The copies are inferior in quality because the dye tends to spread and ink on the copies tends to fade with time. The clarity of the image becomes progressively weaker as the copies are rolled out. It is difficult to alter the master copy if there are mistakes in the master.