Clamshells

The main feature all clamshells have in common is they enclose the entire product as well as the print card.  Since they rely completely on plastic for their strength, they can hold heavier items than a seal blister that relies partly on paperboard. This strength also increases their volume potential allowing clamshells to hold larger and more numerous items. In addition, they provide good stability because the front and back portions of the plastic can be designed so the product rests on its center of gravity.

Two-piece Clamshell

Two-piece clamshells use two pieces of plastic which fit snugly together. Often the front and back part of the plastic is conformed to the shape of the product. However it is also common to make the back of this packaging flat, leaving only the front plastic conforming to the product. This type is usually sealed closed using high frequency welding, making it not resealable once opened.  Welding them together provides greater assurance that the package does not come apart in transport or when dropped. In addition, two-piece clamshells are often used for electronic merchandise since the high frequency welding makes them difficult to open and acts as a theft deterrent. To prevent frustration by the end user in opening the package, a section in the back of the blister can be perforated.

Two-fold Clamshell

Two-fold clamshells consist of using one piece of plastic which has a hinge-like bend at the bottom. The front and back is usually conformed to the shape of the product, resting the items on their center of gravity. This type of clamshell is also used more often than others as a container for multiple small items such as nails. In this case they do not conform to the product themselves. Both interlocking tabs and high frequency welding are used with two-fold clamshells.

Tri-fold Clamshell

Tri-fold clamshells consist of one piece of plastic that takes a triangular shaped when closed. This provides more stability for larger or heavier items. Whether the plastic is flat or conforms to the product varies greatly with this type depending on need.  Like a box, tri-folds allows more versatility in retail store placement since they can hang or stand alone on a shelf. Both interlocking tabs and high frequency welding are equally seen. In the picture above, the tri-fold clamshell makes use of both of these closure methods. The interlocking tabs help to keep the product pieces in place while the high frequency welding ensures that the packaging will not open prematurely.  Because more plastic is needed for tri-fold clamshells, it is generally more expensive than other clamshell types.