Packing an insulated bag correctly: seven points
An insulated bag only works if it is properly filled and properly sealed. These seven points determine whether your shipment arrives at temperature. After that come the practical pitfalls, a checklist and answers to questions that shippers often ask us.
Start with chilled product
The bag insulates, it does not cool. Product that has already warmed up will not return to temperature. Fill the bag in the chilled space.
Coolant on top
Cold sinks. Place the cold packs on top of the product, not underneath. For larger bags, distribute them: some on top and some along the side. You can read how to prepare cold packs in freezing and packing ice packs.
Seal the bag properly
A bag with an open top is only half as effective. Use the adhesive strip or seal with tape. Air circulation is exactly what you want to prevent.
Fill the remaining space
A half-full bag contains air in which heat circulates. Fill the space or choose a smaller size. That makes more difference than an extra layer.
Use an outer box
The bag insulates but does not protect against pressure or impact. For parcel transport, place the bag in a cardboard box. For deep-frozen goods, that box also catches the condensation.
Prevent direct contact
With frozen cold packs, the product can freeze on. Place a sheet of cardboard between product and cooling if freezing on is undesirable, for example with fresh vegetables or pastry.
Check before shipping
Is the adhesive strip properly closed? Is the coolant on top? Is the bag full? Three checks that cannot be corrected afterwards.
How to choose the size
First measure your product, including the inner packaging. Add the space for coolant to that. Then choose the smallest bag in which everything fits neatly. A bag that fits tightly is less prone to shifting, and there is less air in it that can warm up.
Also look at the fold at the top. With a full bag, you need a few centimetres to fold the bag over properly and tape it shut. A bag that is filled to the brim never closes properly.
Common pitfalls
- Closing the bag too late. Every minute open is a minute in which warm room air goes in. Make sure everything is ready before you start filling.
- Cold packs that are not frozen through. A pack that feels hard on the outside can still be soft inside. Freeze them well in advance.
- Damp product in the bag. Condensation and moisture weaken the adhesive strip. Dry the product before you pack it.
- Using the bag as a cushion. An insulated bag does not protect against pressure. Do not stack heavy boxes on it.
- Reuse without checking. When reusing, check whether the film is intact and whether the adhesive strip still sticks properly.
By type of product
Fresh product that must not freeze, such as vegetables, pastry or dairy, calls for a layer of cardboard between cold pack and product. Deep-frozen products, on the other hand, benefit from cold packs that lie directly against the product. For this application we offer separate pages: insulated bags for frozen products and insulated bags for foodstuffs.
Do you ship liquids or products that can leak? Then first place them in their own sealed inner packaging. An absorbent layer in the outer box can help to catch spillage. Take a look at our absorbent pads for this.
Test your set-up before you scale up
Every combination of product, bag, coolant and route is different. The actual holding time depends on the outside temperature, the filling and the amount of coolant. Therefore do a trial shipment first. Place a data logger in the bag and read out the temperature curve after arrival. That way you see whether your set-up has sufficient margin. You can find data loggers in the collection data logger.
Checklist for packing
- Product is at the right starting temperature.
- Cold packs are completely frozen through.
- The bag is the right size and full.
- Coolant lies on top, with larger bags also along the side.
- There is a cardboard separation where freezing on is undesirable.
- The bag is sealed with adhesive or taped shut.
- The bag is in an outer box that encloses the bag well.
Instructions for the recipient
Good packaging also needs good receipt. State on the box that the contents are chilled and must be unpacked as soon as possible. Do not let the recipient leave the bag standing in the hall for hours. For shipments to business customers, a short line on the delivery note helps, so that the right department puts the parcel straight into cooling.
Frequently asked questions
Can I reuse an insulated bag?
You can if the bag is undamaged and closes properly. Look for small tears, loose seams and the adhesive strip. If in doubt, use a new bag.
Do I always need an outer box?
For parcel transport we do recommend it. The outer box gives rigidity and catches condensation. For internal transport it may be different.
When is an EPS box a better choice?
If your product is fragile, heavy or a long time in transit, a rigid box is often more practical. You can find a comparison in insulated bag or EPS box.
How many layers do I need?
That depends on the duration of the route and the season. Read insulated bag: 2, 4 or 6 layers for this. Also take a look at the complete range of insulated bags.
