What makes a cardboard food tray leak-proof

Untreated cardboard absorbs liquids. What holds cooking juices, vinaigrette or sauce is the layer applied to the inside of the container, and it is not always visible to the naked eye. Two main types are available, with very practical differences in use.

Varnished cardboard

A food-grade varnish applied to the cardboard provides leak resistance and grease resistance. The container can hold both cold preparations and hot food when being filled, but it cannot be reheated. This is an important limitation to know before handing it to a customer who will be taking the meal away.

Cardboard with a plastic coating

A PP-type plastic coating applied to kraft cardboard changes the equation: it provides good resistance to moisture and grease, and microwave use is possible for products that specifically state this. The cardboard remains the main structural material, while the plastic provides the barrier. This functional coating principle is also found in the cardboard pots and cardboard bowls in the catalogue. For different performance and presentation, wooden food containers meet other serving requirements.

Filled hot, reheated or served cold: three situations not to confuse

During the rush, nobody has time to reread a technical data sheet. The tray is filled, closed and placed in a refrigerated display, and it is the customer who will discover at home whether it can be used in the microwave. The decision therefore has to be made when ordering, not when serving.

Filling hot requires resistance to the temperature of the food at the time of packaging. Reheating requires something different: resistance to an additional source of heat, whether an oven or microwave. Serving cold only requires leak resistance. Some products in the range can be placed briefly in an oven at a moderate temperature and reheated for a short time in the microwave, with the recommended duration and power specified on the product sheet. Others are suitable only for hot filling. With takeaway food, reheating takes place outside your kitchen, leaving you no opportunity to correct the wrong packaging choice.

The lid matters just as much as the container

Three closure systems are available. The hinged lid is integrated into the tray, as with kraft models featuring a transparent window: only one product reference needs to be ordered and there is nothing to assemble during setup. The separate lid clips onto the tray and may sometimes be held in place by handles folded over the sides. A lid sold separately requires an additional order line and therefore separate stock management.

The transparent window, made from PET or cellophane, allows the contents to be seen without opening the container. This is useful in display cases, for click and collect and for any snacking packaging where the product is first sold by its appearance.

One point deserves systematic checking: the heat resistance of the lid is not necessarily the same as that of the tray. A container suitable for microwave use may come with a transparent closure that is not microwave-safe. The product sheet specifies the characteristics of both separately.

Storage space and restocking strategy

Storage space should be measured in linear metres before being measured in euros. A rectangular shape that maintains the same footprint across several heights, with a common lid for those heights, avoids multiplying storage locations and order lines during restocking. The rectangular kraft trays with a plastic coating follow this principle. Trays that can be stacked once closed also help free up storage space.

Packaging quantities are part of the same calculation. A large carton reduces the unit price, but it takes up storage space and slows down stock turnover for a product that is used only occasionally.

Takeaway or on-site dining: two different situations

Since January 2023, the French AGEC law has required reusable tableware for on-site dining establishments serving more than twenty customers simultaneously. Cardboard food trays are intended for takeaway and delivery, outside this specific scope. For table service, reusable solutions should therefore be considered.

When it comes to end-of-life, four terms are often confused: recyclable, reusable, deposit-return and compostable. They do not mean the same thing. Some products in the category are indicated as recyclable, while others specify domestic composting certification. This information should be checked product by product rather than inferred from the material alone.

Comatec, a cardboard food tray supplier for foodservice professionals

Each product sheet specifies where the product was manufactured, in France or Europe, and FSC® and PEFC certifications are displayed on the products concerned. Each sealable capacity has a corresponding lid reference, making seasonal restocking easier. The cardboard presentation trays follow the same product-range approach.

Requesting samples remains the safest way to assess the actual capacity and performance of a tray with your own recipe. Delivery is free for orders over €350 excluding VAT.