¶Packaging Basics

Application and Removal Torque: The Science Behind a Properly Sealed Screw-Cap Closure

Queenie Fong

August 24, 20263-minute read

Application and Removal Torque: The Science Behind a Properly Sealed Screw-Cap Closure

Bottle cap application on automated production line

Torque tester measuring removal torque on a screw-cap bottle

Technical schematic of a torque measurement system

?FAQ

Frequently asked questions

What is application torque?+

Application torque is the rotational force used to screw a closure onto a bottle, measured in pound-inches (lb/in). A common rule of thumb is that application torque should be approximately 50% of the closure diameter.

What is removal torque?+

Removal torque is the maximum force required to unscrew a closure from a bottle. It is measured 24 hours after application and should be between 40% and 60% of the application torque due to back-off relaxation.

Why should removal torque be measured at 24 hours?+

Closures back off over time as the cap relaxes against the bottle threads. The amount of back-off depends on the closure material, bottle neck finish material, environmental conditions, and storage time.

What equipment do I need to measure torque?+

A torque tester is required, either manual for small batches and QC spot-checks, or automated for high-speed fill lines and continuous process monitoring.

Is tighter always better for screw-cap closures?+

No. Over-tightening causes thread stripping, cap shearing, jumping, and bottle cracking. The correct torque ensures a leak-proof seal without damaging the closure or container.

Written by

Queenie Fong

Queenie Fong is the founder of Propack Solutions, a woman-owned sustainable packaging company based in Ontario, CA. With nearly a decade of experience in the packaging industry, she specializes in post-consumer recycled (PCR) materials, helping brands source rPET, PCR HDPE, and PCR PP packaging that meets regulatory requirements and sustainability goals.