The reject is used for placing the lining of plaster, but before that, it goes through a productive process of selecting, cleaning and cutting.
Although the plasterboards are male and female, it can not use any mass amount of plaster to unite them. So a rip is made in both plasterboards and found an ideal point to be completely filled with a mass of plaster mixed with sisal, forming a league, a point of union between the two boards. The mass of plaster mixed with sisal provides the necessary stability to the partition.
It is therefore considered to be a special product for installation of the liner in order to provide durability, adhesion and resistance of the plasterboard