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Environmental pressures are triggering a move away from heat seal blister packs. But clamshell packs are becoming popular for their ability to add value and protection to an array of consumer applications – from herbs to doorknobs – Louise Hunt reports

In consumer applications, heat seal blister packs are losing their appeal for the environmental reason that it is very difficult to separate the card from the plastics for recycling. Clamshell packs are becoming a popular solution as they can be separated, while offering a number of aesthetic and protective benefits.

Paul Smith sales and marketing director at vacuum forming specialist Charpak says the hardware industry is particularly receptive to clamshell packs. Small items such as screws were traditionally packed in skin-packs. Now they are either found in polythene bags or, when a more upmarket and security conscious pack is required, clamshells are called upon.

A recent clamshell project was for Artex-Blue Hawk for its re-launched coving accessories. The parts were previously sold in pairs, loosely enclosed in a polybag and topped by a folded and stapled header card.

Charpak was asked to develop a solution for four accessory types in three sizes of coving. Three pack sizes relative to the coving depths were chosen. A further feature to the design was to nest the pairs of accessories and display them as they would appear on the ceiling. In-house toolmakers designed the vacuum formed packaging to closely follow the fluted contours of the products.

Clamshell packs have the added advantage of being able to incorporate tamper evident features through welding. Charpak supplied the coving packs with Charlok clips.

Annual sales of the visually striking pack are said to have increased by 60%.

Product security has become a major issue for Manchester based Mr Blister, which makes a large range of off-the-shelf blister packs used across the retail sector. Managing director Gary Briscoe explains the story behind Virtuweld – ‘the folding blister pack that thinks it’s welded’.

“While blisters have enjoyed success over the past decade due mainly to the all round visibility and protection they give to products, it became apparent to us that a potential area for improvement was the security of the packs. Many retailers were expressing concern over pilferage and components “falling out” in store.

“We therefore decided that our new blister designs had to feature a strong seal without our customers needing to use sealing equipment, such as staples and adhesives as well as minimising shelf space and being quick and easy to pack.

“The end product was a breakthrough in the use of dynamic retention to create a really strong seal and, by adding a ‘stitch’ effect on the edge of the blister, we created a blister that looks and feels like a welded pack without the hassle and cost of secondary sealing.”

Mr Briscoe says Virtuweld has been well received. Its launch has also provided a cost-effective alternative for companies who are being forced to change from non-recyclable packaging such as blister carding and skin carding.

“By using a minimum of 50% recycled material in the manufacturing process and making the blisters so that they can hang or stand, we believe that the Virtuweld has ‘secured’ the future for blisters,” adds Mr Briscoe.

The Visual Display Packaging Division of Sharp Interpack – formerly M.Y. Plastics – is also finding success in consumer applications that require point of sale distinction.

Since its change in ownership in May 2002, Sharp Interpack is aggressively chasing leadership in the non-food blister packaging sector through investment into new thermoforming technology and expansion of its blister sealing options.

“We have the capability to supply not only blisters, insert trays, and hinge packs but a comprehensive range of blister sealing and RF welding machinery,” said Mark Tollman, general sales manager – VDP. “We can help clients achieve guaranteed running rates which helps them to reduce costs and speeds up the development process.”

Two projects to benefit from the investment were for Zebra Pens in June 2002 and SCJohnson’s Glade Circulair plug-in room fragrances launched this February.

The Zebra Pens project involved the supply of an alloyed 4SCBE automatic heat sealing machine from Sharp that can handle 1.4M pen packs in-house. The machine also puts the blister and blister card in place and ejects the product, which means that output speed is only limited to the placement of the product.

Sharp Interpacks’s thermoforming skills were put to the test with Circulair which required a pack that was visually interesting, fully sealed, free standing, robust and delivered within a strict time frame.

The diversity in applications for clamshell blister packs has this year led Stockport based vacuum formed packaging manufacturer Macpac to branch out of its core bespoke blister packaging business with a comprehensive range of stock blister packs.

Based on Macpac’s Eurocell self-locking blister, the BlisterKing range addresses problems commonly associated with blister packs. These include limited selection of size and shape, inadequate fit, weak blisters and poor product protection, explains managing director Bob Bolton.

“The BlisterKing project has undergone more than two years of research and development to assess the most practical designs for the widest possible customer base. It also required a significant capital investment and extensive original CADCAM tooling to produce over 100 shapes and sizes.

“BlisterKing packs are designed to give greater strength reducing potential damage, consequently improving their appearance at point of sale while remaining price competitive.”

The concept behind the improvements was to move from the conventional convex ‘female forming’ method of production. This enhances peripheral pack strength but reduces profile strength and consequently product protection, says Mr Bolton.

“BlisterKing uses the concave male thermoforming technique promoting extra strength to the extrusion profile where it is most needed. Any peripheral pack weakness is compensated for with an ingenious profile design resulting in a far stronger pack.

“The net benefit of this is the option of superior pack strength at no extra cost or reduced costs where pack strength is not the key issue by manufacturing from thinner grade substrate. This reduction of raw material consumption has obvious environmental implications that are further enhanced because the BlisterKing range can be manufactured from recycled APET.”

The BlisterKing range is supplied with a ‘flip and clip’ tab-locking device designed to reduce pilfering or tampering with the product. If the product demands a higher level of protection there is the option to high frequency weld the seams.