The oil lamp

by Kavitha — November 17, 2020

It is the time of the festival of lights in India. Lamps light up the entire country and people rejoice in the festivities. As I sat watching the bright flickering flames from my balcony, I was curious to know how these oil lamps work. Eager to explore this? Read on…

Oil lamps have been used since centuries for lighting up homes in various civilisations across the globe. What do such lamps consist of in general? The basic components seen in the earthen lamp before me would be a wick, oil, and the receptacle to hold the oil. If we were to take the oil lamp as an instrument or machine and look at it, one would see the following parts – a fuel tank, a pipe to conduct the fuel to the ignition tip and the fuel itself.

The fuel tank is the receptacle to hold the oil and could be of varying shapes and sizes. Large tanks would obviously hold more fuel as compared to smaller ones. The tank could be open as in the earthen lamp, or a floating wick lamp (which is nothing but a cork with a wick in its centre and both ends sticking out; this is then left afloat on a container with the fuel). They could also be closed like the humble kerosene lamp or the ones used by the railways to signal oncoming trains (of course in olden days since they are now replaced with electric lamps). Ideally, most of the containers are made of materials like clay etc. which do not conduct heat and can also be provided with a handle to facilitate easy transport. Materials used to make this tank include clay, stone, glass, metal etc.

The next part of this lamp instrument would be the fuel. The fuel which is housed in the tank would be any combustible liquid mainly oils. Oils of many varieties are used in burning lamps, the most common being used in Indian traditional lamps being Ghee or clarified butter, vegetable oils etc. Castor oil is also used widely to burn lamps. Fish oil which was once a popular choice as fuel was very soon replaced due to its smoking property and the weak flame it generates. Palm oil, canola oil, coconut oil, sesame oil and lamp oil are some types of oil being used in lamps as fuel. Kerosene is another popular variant also called as ‘wax oil’ which produces a bright flame unlike the other oils used in lamps.

The key rule in selecting a suitable fuel is to ensure that they are not too ignitable like alcohol, gasoline etc which may result in dangerous consequences like explosions due to the heat generated during the burning process. Nowadays additional aromatic oils are used to enhance the ambience of the place where the oil lamps are lit. In addition citronella oil, lemongrass oil added to the fuel help ward off insects and mosquitoes when lit.

The wick is made of any cotton or natural fibrous material like hemp, linen, and other plant fibres. The upper end of the wick is in the air while the lower end dips into the fuel tank and is in contact with the oil. The fuel travels up the wick by capillary action to its tip where the flame vaporizes the fuel and burns continually as more fuel is sucked up the fibrous wick till the fuel burns out. The length of the wick can be adjusted in some lamps which in turn controls the brightness of the flame. Earthen lamps have a pinched side on one end to keep the wick in position as it burns while others have a wick hole through which the wick passes through and is held in place.

Now that we have looked at the traditional lamps as a machine, let us also remember the deep traditions and cultures associated with lamps in different countries. Next time you see one, look at it in detail and try to understand the science behind this instrument and also enjoy the history and intricate design of the lamp you behold.