What is the difference between standard water-based cold packs and specialized phase change materials?

Standard water-based cold packs primarily contain water or water-based gel. They undergo a phase change at approximately 0°C (32°F), which makes them ideal for maintaining refrigerated temperatures.

Specialized phase change materials (PCMs) are formulated with materials such as salt hydrates, paraffin waxes, or other chemistries that are engineered to change phase at specific temperatures. These can be designed for higher or lower temperature set points, such as deep refrigeration (e.g., -20°C) or other controlled ranges, depending on the application.