Scholander pressure bomb

As the pressure increases, at some point the liquid contents of the sample will be forced out of the xylem and will be visible at the cut end of the stem or petiole.

The pressure that is required to do so is equal and opposite to the water potential of the sample (Ψleaf or Ψtotal).

[5] Additional variables and methods that involve pressure bombs for analysis include: stem conductance, xylem embolisms, and vulnerability curves.

As water is forced out of the sample with each measurement in the pressure bomb the mass is also reduced.

Tracking these changes over many measurement should show a precipitous drop and then a steady linear decline after an inflection point.