The pressure light of the mosaic machine doesn't work, not because there is too much mosaic powder, but because the handwheel doesn't turn clockwise. Because the pressure lamp of mosaic machine needs to be turned on and then turn the handwheel clockwise immediately until the pressure lamp is on, otherwise the sample will be scrapped because of insufficient pressure. Mosaic machine is suitable for pressing unformed and difficult-to-take-out microscopic metallographic samples.