The best theft protection for retailers, but in many cases anightmare for consumers to open.

Clamshell blisters, are extremely popular with retailers due to the fact that there is almost no packaging that gives better protection against in-store theft. To increase the theft protection of clamshell blisters even further, very often security labels such as HF or ultrasonic alarm tag labels are positioned inside the plastic packaging. Unless customers are equipped with scissors or a knife, this kind of packaging is extremely difficult to open in the store thus giving the best protection against pilferage.

The downside of extremely good theft protection is that, once at home, clamshell blisters are very hard to open,even when using a knife or scissors. Unfortunately many cases are known where customers get injured while opening clamshell blisters.

Clamshell blisters are widely used to pack up-value consumer goods, sold in a DIY, or self selling (warehouse) environments. Products such as electronics, computer hardware, sanitary accessories, automotive parts etc. are often packed in a clamshell blister.

Materials

Clamshell blisters usually consist of athermoformed front blister and a back blister (or flat plastic sheet) with apiece of cardboard or paper trapped between the blisters.

Depending on the size of the blister and the desired strength, the thickness of the plastic can be adapted to the specific requirement. The plastic is usually a PVC, PET-A, PET-G or PET GAG.The insert piece that carries the communication and product information is madeof printed paper or cardboard.

Sealing

Clamshell blisters can either be sealed,using high frequency sealing, ultrasonic sealing or simple heat sealing. Thechoice of sealing depends on the type of plastic that is being used.

In case PVC, PET-G or PET-GAG (Glycol modified polyethylene terephthalate) isused, it is possible to use induction or radiant heat sealing. The best heat-sealing results can be achieved in case the patent pending is used.The advantage of this hot-cold technology is that the sealed blister flanges will not become brittle and that they will become flat and strong aftersealing. Conventional heat sealing is possible, but expect blister flanges tobecome a bit brittle and curled.

In case A-PET is used, high frequency sealing or ultrasonic sealing are the best sealing techniques.