What is the material of the oldest blackboard?

There are many kinds of blackboards, from the earliest cement blackboards and wooden blackboards to the frosted glass blackboards in the 1990s, and now to coated steel plates, enameled steel plates and composite plates. It can be said that each generation is better, not only in quality, but also in technology, making it more and more convenient to use. Now cement blackboards and wooden blackboards are basically eliminated. The following blackboard manufacturers introduce blackboards by material classification.

First of all, the traditional cement blackboard, limited by construction conditions, is prone to cracks and fading, which also affects vision;

The second is a wooden blackboard. Because it is wooden, it is more easily restricted by climatic conditions and easily deformed by moisture.

The third is the glass blackboard, which is not easy to move and easy to break, and the size of the glass blackboard can't be changed at will. At the same time, it is also damaged in transportation, and people are cautious in maintenance.

The last one is painted steel plate, which can be said to be the most popular at present. It is characterized by fine and smooth writing, clear handwriting, hard wear and good hardness, which has a good effect on protecting eyesight and is of great help to teaching and people's lives.