Plastics

Plastics tend to be brittle at deep freezer temperatures and boxes must be handled without physical impact while cold.

  • Polypropylene (PP) is one of the most suitable plastics for cold storage and recommended down to -80°C.

  • Polycarbonate (PC) is recommended down to -190°C.

  • Polystyrene (PS) is occasionally used for cryo storage containers. It is light and can maintain structural integrity at ultra-low temperatures. The bulkiness of PS is a potential drawback. 

  • Eastman Tritan™ is a copolyester, engineered for superior performance in cryogenic conditions. It is a shatter-resistant yet boasts excellent clarity and colourability. 

Specifications polypropylene vials*

They can withstand temperatures from +121°C down to -196°C.

Freezing - volumes should be 10% less than listed capacity.

Filling - the cryo centrifuge tube should be filled with no more than 90% of the tube's volume (to permit expansion). Upon freezing, ensure that the entire vial is frozen at the same temperature - avoid racks that create partial insulation. The cryo centrifuge tube should be moved periodically during freezing to avoid supercooling and subsequent quick ice formation.

Freezing in liquid nitrogen - ensure that the screw cap is not overtightened. The thread and screw cap of the vial should be completely dry before closing; liquid drops will impair the seal in liquid nitrogen. 

Storage - vials should be stored in the gas phase above liquid nitrogen. If they are immersed, the vials might develop leaks or even shatter when returned to temperature.

Removing vials from liquid nitrogen containers - always use safety equipment such as gloves, hoods, face shields etc. To thaw, place the vial into a water bath (37-40°C) and keep it in constant motion. As soon as the ice has melted, remove the vial from the water bath. 

*some models may contain silicone washers

Cardboard

Treated cardboard is resistant to moisture and more durable than regular cardboard. No brittleness temperature effect makes cardboard superior at lower temperatures down to -80°C. 

Metals and Metal Alloys

Stainless steel, aluminium and some alloys are used for constructing cryogenic storage dewars and freezer racks. This provides durability and resistance to corrosion, making it suitable for long-term storage of larger quantities of samples.  

Silicone and Rubber

These materials are used for sealing gaskets and O-rings in cryogenic containers, ensuring an airtight seal to prevent moisture and contamination.