According to Wikipedia, A chalkboard or blackboard is a reusable writing surface on which text or drawings are made with sticks of calcium sulfate, known, when used for this purpose, as chalk. Blackboards were originally made of smooth, thin sheets of black or dark grey stone stone. Modern versions are often green or brown and are thus sometimes called a greenboard or brownboard instead.
A chalkboard can simply be a piece of board painted with matte dark paint (usually black or dark green). A more modern variation consists of a coiled sheet of plastic drawn across two parallel rollers, which can be scrolled to create additional writing space while saving what has been written. The highest grade chalkboards are made of a rougher version porcelain enamelled steel (black, green, blue or sometimes other colours). Porcelain is very hard wearing and chalkboards made of porcelain usually last 10-20 years in intensive use.
Chalkboards have disadvantages: they produce dust, the amount depending on the quality of chalk used. Some people find this uncomfortable or may be allergic to it, and there has been speculation about links between chalk dust and respiratory problems. The dust also precludes the use of chalk in areas shared with dust-sensitive equipment such as computers. However, these alternative methods of displaying information have drawbacks of their own.
Why sometimes it is called chalkboard and sometimes blackboard? Whats are the different? We will cover this story in the next post.
( Magnetic Chalkboard Paint )