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Case Studies / Extraction Testing of Whisky Stoppers

Extraction Testing of Whisky Stoppers

Solution

Software-driven combined cork extraction testing system
Custom-built software modules for simultaneous force and torque measurement

Benefits

High precision and consistent evaluation of complex extraction behaviour
Enhanced assurance of sealing integrity and product safety
Capability for cyclic testing to simulate repeated opening and resealing

For premium whisky bottle stoppers, one of the most important things that they need to be capable of is a tight seal, and at the same time, they should also be easy to open. It is essential for manufacturers to have precise testing of extraction force and release torque for assessing stoppers' reliability, lubrication performance and their ability to withstand repeated use in the long run.

Presto provides a software-controlled, combined force and torque testing system for whisky stopper extraction analysis. Both the real-time torque and the pull force are registered, and the extraction forces are applied both rotatively and vertically to simulate real opening conditions. Cyclic testing, graphical analysis, and custom reporting are provided by advanced software and come in handy when it comes to ensuring premium bottle closures, ensuring product quality, sealing performance, and consumer satisfaction.

Requirement

To improve the performance and protect their premium high-value product, the R&D team at a leading Scottish whisky manufacturer worked on optimizing the design of their reusable bottle stoppers. They identified that ensuring reliability required detailed and systematic testing of both sections of the stopper assembly.

For the cork segment, critical parameters included compatibility with the bottleneck finish and the effectiveness of cork lubrication. For the bar-top section, the focus was on the bonding strength between the cap and the cork body.

The decorking process involves two key actions. First, a rotational motion initiates loosening, meaning the applied torque must remain within acceptable limits. Second, the stopper is pulled out vertically, requiring the extraction force to also fall within defined thresholds. Additionally, the stoppers were required to meet ISO 9727-5 standards, which define the method for determining the maximum force needed to remove cylindrical cork closures.

Solution

Working closely with the client’s R&D team, Presto developed an advanced combined extraction testing system that can simulate both twisting and pulling actions simultaneously. The system consists of a manual chuck to hold the stopper and a special bottle holder to hold the bottle.

The cradle is moved up and down via threaded columns and thumb fasteners, and the bottle is securely clamped using quick-locking devices. As part of the test, the chuck spins in the counter-clockwise direction, and the cradle is displaced down, replicating real-world conditions. Data on the torque and extraction force is gathered as the stopper is ejected, with the test process ending when the stopper has been ejected.

For durability analysis, cyclic testing can be programmed to evaluate repeated opening and resealing performance. In this mode, the system performs the reverse process, lifting the stopper clockwise while raising the bottle to reinsert the closure.

All torque and force data are captured through integrated software platforms and compiled into customized reporting formats, enabling clear statistical and graphical analysis. The system can also be adapted with additional fixtures to perform shear and tensile testing between the cork and bar-top components.