From the experimental results, it has been found that the molten bonding pellet, which is obtained by drying slowly a green pellet in a vinyl chloride bag, shows the strength as much as one thousand times of the strength of dry pellet. When the molten bonding is not formed enough, the strength of this pellet can be expressed by the same equation (3) as that for dry pellet. When the molten bonding proceeds, the strength of the pellet can be expressed by the equation (4) independent of particle diameter.
This phenomenon could be explained as follows:
Na and K constituents in glass pellet dissolve first into water contained in a pellet and congeal to solid state again as the pellet is dried slowly in a vinyl chloride bag. Consequently, the volume of pellet shrinks like in the sintering process as it dries.