How to Keep Things Cold During Shipping

If you’re shipping perishables that need to be maintained at a specific temperature range, you need to make use of cold chain technologies to keep the temperature of your goods safe and consistent throughout transit. Shipping perishables the right way is crucial to ensuring that they arrive in good condition.

You need to use cold shipping boxes to keep your perishables insulated against overheating or, in the winter, freezing (which can be just as damaging to temperature-sensitive foods as overheating). You need to pack shipments with the right refrigerants to keep them at the desired temperature range. Finally, you need to plan ahead to make sure they’re delivered quickly.

Use Cold Shipping Boxes

You can buy cold shipping boxes or insulated shipping boxes directly from the shipping carrier, or you can buy them online at retailers like Amazon and Staples. Polystyrene shipping boxes are sturdier than styrofoam boxes, so they’re a good choice if you’re using a carrier like USPS that doesn’t offer any temperature-controlled shipping options. The thicker the polystyrene or styrofoam box, the longer it will keep your shipment cold. Some carriers may offer temperature-controlled shipping, which may be worth it if you’re relying on cold chain technologies to help you ship perishables produced and sold by a small business. 

Pack your cold shipping box inside a larger cardboard box. Put some additional insulation, like thermal bubble wrap or styrofoam panels, inside the cardboard box to hold the styrofoam box in place and minimize impact damage to your package contents.

Pack Shipments with a Refrigerant

woman holding a carton box

You’ll need to pack perishable food and other temperature-sensitive items with a refrigerant to keep them cold or, as the case may be, frozen. If you want to keep package contents completely frozen, dry ice is the refrigerant of choice. Dry ice is carbon dioxide in its solid form. Its temperature is about -109 degrees Fahrenheit. Unlike water ice, dry ice does not melt into a liquid, but instead sublimates into carbon dioxide gas. 

So, if you’re shipping frozen foods with dry ice, you can’t put them in an airtight container. The carbon dioxide needs to be able to escape from the packaging. Dry ice can also be dangerous to ship via air. You will need to comply with your carrier’s rules for shipping packages with dry ice. Those can include limits on how much dry ice you can put in a package, restrictions on where you can ship packages containing dry ice, and requirements for labeling packages containing dry ice. As dry ice is considered a hazardous substance, you will need to label the package with the quantity of the dry ice within as well as other information. 

If you’re shipping perishables that need to remain cool but not necessarily totally frozen, you should use gel packs. Gel packs can be frozen and packed around perishable items like fruit, chocolate, live seafood, and baked goods to keep them fresh in a styrofoam or polystyrene cold shipping box. Gel packs will sweat some liquid as they warm up, so you’ll need to wrap your perishable items in watertight plastic (except for live seafood – it needs to be allowed to, quite literally, breathe). Line your outer cardboard box with plastic and place an absorbent pad in the bottom of the box to soak up any moisture that may leak out of your cooler. This will keep the outer box from getting wet and soggy.

Plan Ahead for Fast Delivery

Even when shipped in the thickest polystyrene box, refrigerants only last for about 48 hours, and even that is pushing it unless you have a lot of dry ice in a large cooler. Plan to get your perishables delivered within 30 hours; use the fastest shipping option your chosen carrier offers. Keep them cold or frozen right up until you pack them for shipping and then ship them immediately. 

Ship your perishable items early in the week so that they won’t get delayed over a weekend, because even if you use a lot of dry ice or gel packs, it might not last long enough for a two-day delay. If you’re shipping perishables for your own use, make sure there’s someone home at the destination to receive the package and transfer the contents into a refrigerator or freezer immediately.

Keeping things cold during shipping requires the right mix of cold chain shipping supplies and a fast delivery service. With the right coolants and insulation, and overnight shipping, you can make sure your perishable goods arrive where they’re going perfectly intact.