In order for a package to function properly, protect without leaks, the closure needs to be applied properly to the bottle being used. In the case of continuous thread closures, typically hand or machine applies the closure to the bottle. In order to create a good seal the appropriate amount of application torque needs to be applied make the system work, whether it is a liner, crab claw, V seal, plug seal, or induction seal.

So how do we know what the correct amount of application torque is for certain size closure? Well, there are two ways; the first way is to consult your closure manufacturer and ask for the recommended application torque for the closure you are using. These values are typically readily available and in some cases even supplied on the product drawing of the closure. The second way to know the correct amount of application torque, review the general guidelines set forth by SPI (Society of the Plastics Industry) for sizes 8 to 132mm neck finishes. These ARE guidelines, and anytime a closure supplier gives their recommendation on application torque, those would supersede the general guidelines, but they are a good source to start from if you have no reference. You can find them here: http://www.tricorbraun.com/KnowledgeResources/TechnicalInfo.aspx

Next question would be: how does the filler know what application torque they are applying to you package? Typically their equipment cannot measure application torque, so they rely on measuring the immediate removal torque. Immediate removal torque is typically 40 to 60% of the application torque, so using this guide helps in setting up the capping equipment properly.

So if you are getting leaking packages or closure back off, one of the first things to inquire about is the amount of application torque being used. Many times the filler may not know that the closure supplier has a specification regarding application torque for a specific closure and that may be all it takes to gain functionality and fix your package’s leakage problem.