What? There’s a shortage? You may have noticed recently, closures with pressure sensitive liners have been difficult to get your hands on. Lead times have been grown up to 16 weeks in some cases. Forcing packaging suppliers and manufacturers to look for alternative solutions for their customers.
How Do Pressure Sensitive Liners Work? - The key element in a PS liner is the adhesive. Which consists of tiny, sealed bubbles of said adhesive that are applied to the underside of the liner. Once the cap is screwed down, the pressure applied by the cap to the liner and bottle neck, bursts the bubbles, releasing the adhesive. Thereby sealing the liner to the neck
Limitations and Availability - The delays in availability are due, in part, to a shortage of polystyrene foam, and the special adhesives that are used in the manufacture of pressure-sensitive (PS) liners. There are concerns about the sustainability of these liners. These liners cannot be recycled. In addition, these liners don’t provide a reliable seal.
Expensive to Manufacture - There are a limited number of US based manufactures that produce the PS liners. Producing the liners are problematic. When cutting the liners for the caps the dies get glue build up which requires constant cleaning. This, therefore, adds additional costs to the process.
Environmental Sustainability - The materials used for the foam liner and adhesive have become focal points of concern for the environmentally conscious. Polystyrene is not a recycled material at most municipalities. There are other liner options that can be recycled and thus contribute to meeting many company's sustainability goals.
Limited Application - While PS liners are simple, and cheap to apply. They are best used for dry products only such as spice seasonings, or powder mixes. PS Liners are not able to seal against moisture and oxygen flow and are not recommended for liquid products.
Lack of Tamper Evidence - Pressure Sensitive Liners are not tamper-evident. Meaning that a PS liner can easily be removed and then re-applied again without showing any evidence of tamper. Because of this, they are not FDA acceptable for food safety.
Are There Alternatives? - Absolutely. Depending on your needs. There are a variety of other liner options that you can choose to use instead. From simple, foam liners to heat sealed foil liners. Heat Induction Seal (HIS) Liners are the best solution for a tamper-evident package. HIS liners do require a special machine to activate the liner adhesive. We offer a hand-held version that is capable of handling any closure up to 100mm neck-finish. If you have more requirements for an automated HIS sealing machine, contact our customer service team.
Can I Still Use PS Liners? - Despite some of the disadvantages inherent with using PS liners. There are lots of people who still prefer them. Especially amongst those who package dry spices, powders and hobby products like glitter and paint pigments. We at Aaron Packaging will continue to offer PS Liners for as long as they are available, and we can get them into stock.
How Can I Experiment with Other Liner Options? - We offer FREE samples of nearly all of our closures online. All we ask is that you pay for the shipping. (We use standard US Postal to ship samples to you.). And if you have more questions, or would like some help with choosing the right liner for your product, please contact our customer service team. We will help you get what you need.
