The sheer strength and popularity of Thermoformed APET packaging is acutely evident from its presence in our high street shops. We need look no further than hinged egg cartons, fruit, vegetable and salad clamshells, sectioned and ovenable food trays, and clamshell packaging for small hardware items like nails, nuts, and bolts. ... not forgetting our mobile phone accessories.

However, as much as this type of plastic clamshell packaging and hinged packs securely display the appearance of their contents, they have proved extremely difficult to make tamper-proof without the use of welding, expensive shrink collars or additional labelling. Incorporating any of these tamper proof utilities only adds to the overall cost, so what is the alternative?

UK high street giant Marks & Spencer has chosen to use thermoformed APET packs within its delicatessen food range and party pack nibbles. The advanced plastic packaging uses Virtuweld patented technology developed by Mister Blister.

The virtuweld tamper-proof plastic packing is not new to the high street stores, it was launched over two years ago and proved to be very successful in the non-food market where it enables manufacturers to display products in packs that have the appearance and security of welded packs without the need for any secondary sealing and with many other benefits.

Virtuweld technology provides the packaging with 'dynamic retention', which means that when one side is pulled, the other tightens. The pack seals with a firm friction fit. The challenge for Mister Blister was to work out how to enable people to get into the pack after purchase yet make it as secure as possible whilst on display ... tamper proof.

The solution was to make the back of the pack seal into the front and a stitch-welded effect has been incorporated into the tooling so that the pack has the appearance and security of a welded pack without needing any secondary sealing.