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

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.

Test equipment

• Combined force and torque extraction testing system
• Rotary torque sensor (capacity up to 15 Nm), Digital display unit
• Specialised grips and fixtures for corks and bottles
• Advanced data analysis software
• Customised reporting tools for detailed evaluation