Two horizontal disks of a sample (cast in shouldered rings) are heated at a controlled rate in a liquid bath (up to +80 °C in distilled water or silicon oil, above +80 °C in glycerin or silicon oil) while each supports a steel ball.

The softening-point is reported as the mean of the temperatures at which the two disks soften enough to allow each ball to fall a distance of 25 mm.

Manual Ring & Ball Test Equipment

More details are mentioned in the "Order Number" section