A Guide to Blister & Clam Packaging

This guide will tell you:

What is blister packaging?

A traditional blister pack has a card back and a plastic protective bubble stuck to the front of the card. This bubble can be in any shape including a uniform shape to protect tablets for example, or an unusual shape to protect a less uniform product, like the football figures shown in the image below.

What is clam packaging?

Clam packaging is actually a type of blister packaging. In the industry it is called a clam shell blister pack. A clam shell does not have a cardboard back, it has as plastic back which is hinged to the front of the packaging. It can be hinged at the side or the base of the pack.

The bubble can be evenly sized on the back and front or can be a different size and shape depending on the product inside it.

Is trapped blister packaging different from blister packaging or are they the same thing?

A trapped blister is almost the same as a traditional blister pack but the plastic part that sticks to the cardboard has another piece of cardboard in front of it that is fitted around the shape of the bubble. The plastic then is trapped between two pieces of cardboard.

This makes it more tamper proof as its obvious if the front cardboard has been ripped and it can offer greater aesthetic appeal by covering the plastic.

What products are suited to blister packaging?

Blister packaging is all about protecting the product. If a product is shaped in a way which might make certain parts of it vulnerable, for example the arm of the football figurines picture above, then blister packaging offers a level of protection that a bag or box can’t.

Blisters also keep products clean and uncontaminated, which is why tablets are almost always packed in this way.

They are also tamper-proof, in that, if a tablet package had been tampered with i.e. a pill had been taken out and replaced, you’d be able to see that clearly from a break in the packaging.

Types of blister packaging:

Some common types of blister packaging applications include:

  • Electronic goods
  • Toys
  • Products with delicate parts
  • Products that are vulnerable to breaking such as ink cartridges
  • Tablets

What products are suited to clam packaging?

Clam packaging offers the same kind of protection as blister packaging but works best for products that won’t really fit in a blister package or sets that have lots of different parts. Things like small tool sets, bulb sets, gift sets and cosmetic sets are often packed in clam packaging.

Advantages and disadvantages of blister packaging:

Why use a blister or clam pack for your products?

There are five main reasons to use blister packaging:

  • Visual impact and ability to show the product off
    You can catch the eye of the consumer easily with blister packaging and let the product speak for itself. Blister packed products often stand out from the shelf much better than boxed alternatives.
  • Protection of the product
    The product is protected from damage, kept clean and signs of tampering are made evident by breaks in the package (unlike a box that can be opened and closed without leaving a trace).
  • Harder to steal
    Blister packs, in particular clam packs, are often non-uniform in shape making them harder to conceal if stolen. This appeals to a lot of supermarket chains at present, since shoplifting is a problem.
  • Light in weight
    Blister and clam packaging is very lightweight, saving money on transportation.
  • Clam packaging can be easily recycled
    Clam packaging in particular can be easily recycled since it’s made of pure plastic.

Further Advantages:

A major advantage of blister packaging in the pharmaceutical industry is that it helps to follow prescription routines. The packaging can be marked so that each little pocket holding a pill is numbered or listed by days. It also helps monitor how many pills may have been taken unlike a bottle, for example.

Another advantage is that the foil is easy to break making them easy for older people to use.


The main disadvantages of blister packaging is the extra work and cost it takes to gain all the benefits listed above! Generally then, the benefits outweigh the disadvantages but they are something to keep in mind:

  • Blister packaging tends to cost more than alternatives
  • The process does take a bit longer than alternatives like bottling

What type of plastic is normally used and why?

PET or PVC can be used. Generally PET is used as it is very clear, strong and holds its shape well. PVC is slightly less transparent and can sometimes appear a little yellow.

A step-by-step guide to the blister & clam packaging process:

  1. A traditional heat sealed blister is firstly formed using an aluminium resin tool.  This process can be expensive, which is why it makes most sense to pack a decent number of products when using blister packaging.
  2. The card is then printed. This involves a special printing process which has adhesive in it. When dry it looks and feels no different to normal printed cardboard, but under heat and pressure the glue melts meaning the plastic bubble can stick to it.
  3. The blister is then placed into a specialised part of the sealing machine, known as the sealing jig. The product is then placed into the blister (the plastic bubble) and the carded is added.
  4. The jig is rotated on a turntable and hot metal plate is applied.
  5. Pressure is applied to the plate to seal the blister to the card.
  6. The turntable is rotated again, the final blister pack is removed and packed into outer packaging for distribution.

You can watch the process below:

Or watch a longer process from the series “how it’s made” here:

How does the cost of blister and clam packaging compare to alternatives?

Blister packing is not a low cost option!

A traditional blister pack has high set up costs compared to a single carton, but if the numbers of units to be packed are high, then these costs can be spread across many products.

A clam shell blister, however, can often be sourced as an “off the shelf” product. There are many companies who have a selection of moulds, and a range of standard sizes from their stocks. This saves set up costs, and if utilised well, can be a very competitive option.

Further information:

Our blister and clam services