  Interface undercooling is one of the most significant parameters in the
solidification of colloidal suspensions. However, quantitative measurement of
interface undercooling of colloidal suspensions is still a challenge. Here, a
new experimental facility and gauging method are designed to directly reveal
the interface undercooling on both static and dynamic cases. The interface
undercooling is visualized through the discrepancy of solid/liquid interface
positions between the suspensions and its solvent in a thermal gradient
apparatus. The resolutions of the experimental facility and gauging method are
proved to be 0.01 K. The high precision of the method comes from the principle
of converting temperature measurement into distance measurement in the thermal
gradient platform. Moreover, both static and dynamic interface undercoolings
can be quantitatively measured.
