Adhesive Testing on Capsulated Stoppers

Solution

• Motorised torque testing system
• Custom chuck-grips designed to securely hold capsulated (Bar-Top) stoppers

Benefits

• Quickly identifies stoppers with weak adhesive bonds
• Uniform and reliable gripping of smooth or slippery surfaces

Requirement

Capsulated stoppers can be of T-top, bar-top, or Altop(r) types; they are made of a natural or artificial cork bonded to a cap of wood, PVC, porcelain, metal, glass, or other substances. The stoppers are common in spirits and fortified wine purposes, where the quality can be opened and reclosed many times without spoilage. They are most popular among distilleries, wineries, and bartenders but are particularly important in high-end brands where product integrity is paramount.

Corks' assembly to caps is done using automated machinery or handwork based on the production levels and material. The pasting material should be in accordance with FDA and able to offer a lasting bond that will not fail to take the torque and pulling forces on repetitive usage. Testing the strength of the bond between the cork and cap is one of the basic quality assurance measurements that are undertaken by both the manufacturers and the end users.

Diam France required a reliable and flexible system to assess the mechanical adhesive bond strength across its Altop® range. Altop® and Altop Diam stoppers feature rapid elastic recovery to prevent leakage and consistent closure performance. The solution needed to accommodate varying cap materials (wood, plastic, glass) and diameters while providing accurate and repeatable results.

Solution Implementation

The test setup holds the cork shank in one grip and the bar-top cap in another. Torque is applied to the stopper until either the adhesive bond fails or the cork breaks. The peak torque is recorded and compared to established quality-control thresholds to determine pass/fail outcomes.

A Vortex-dV motorized torque tester delivers rotation at a constant speed, eliminating variability from inconsistent actuation. Peak torque is captured with high-resolution data acquisition, ensuring sudden adhesive or cork failures are accurately detected.

Gripping high-torque stoppers can be challenging due to the smooth surfaces of coated corks and hard cap materials. Presto Stantest made custom-designed chucks having their own dedicated jaws to allow the chucks to hold the two segments firmly. The square-drive mechanism enables the mechanisms to be adjusted accurately to ensure that specimens are held with consistent clamping, neither being strangled nor loosened.

Test Equipment

• Vortex-dV Motorised Torque Tester
• 6 N·m Torque Transducer
• AFTI Torque Indicator
• A pair of bespoke chucks for various capsulated stopper sizes