Particles in the colloid are large enough to be seen in a light microscope. Therefore details of the formation and dissolution of crystal structures as substances freeze and melt can be observed directly, answering questions about these phase transitions in all substances. Some colloidal crystals display unique phase properties, which can be exploited to create new materials.
Supercooled fluids pass through various stages as they crystallize.
Shaking a colloidal cystal completely disrupts its ordering, although the system remains at the temperature and density of the crystalline state. The result is a supercooled fluid, shown at the left of this schematic as a collection of red spheres, in which the stages of crystallization can be seen. The initially homogeneous fluid slowly forms layers against the container's glass walls. The crystal nucleates first in the outer layers and spreads rapidly through the plane. Freezing proceeds more slowly into the bulk of the suspension.