ISO 9727-7:2007

Overview

ISO 9727-7:2007 specifies a standardized test method for determining the dust content of cylindrical cork stoppers (straight cork stoppers) ready for use and intended to be fully inserted in a bottle neck. The method quantifies particulate matter released from corks using a filtered ethanolic wash, membrane filtration and gravimetric measurement. This part of ISO 9727 supports consistent cork stopper testing, quality control and acceptance criteria across manufacturers and laboratories.

Key topics and technical requirements

• Scope: Applies to all types of cylindrical (straight) cork stoppers ready for use.
• Sampling: Test piece = 4 cork stoppers; sampling plan to be agreed between parties.
• Test fluid: 10% ethanolic solution prepared with demineralized water and pre-filtered through a 1.2 µm membrane.
• Apparatus:
  • 500 ml conical flask (bottom diameter ≥ 100 mm)
  • Orbital stirrer (140–160 r/min)
  • Vacuum filtration set and membranes (1.2 µm)
  • Oven options: 30 °C ±2 °C for 24 h (cellulose acetate/polycarbonate membrane) or 103 °C ±4 °C for 1 h (glass microfibre)
  • Analytical balance resolution ≤ 0.0001 g; desiccator
• Environmental/test conditions:
  • Laboratory: 21 °C ±4 °C; relative humidity 60% ±20%
  • Cork temperature: 21 °C ±4 °C
  • Cork humidity: 6% ±2% (if outside 4–8% report in test results)
• Procedure (summary):
  • Place 4 stoppers in 250 ml of filtered 10% ethanolic solution in a 500 ml flask; stir 10 min at 140–160 r/min.
  • Filter the wash through a pre-dried, pre-weighed 1.2 µm membrane. Rinse stoppers, flask and funnel with two 50 ml aliquots, filtering each.
  • Dry membrane per specified oven option, cool in desiccator and reweigh.
• Calculation:
  • Dust per stopper (mg) = (m_final − m_initial) / 4, rounded to 0.1 mg.

Applications and users

• Quality control teams at cork manufacturers to monitor particulate release and production consistency.
• Independent testing laboratories performing acceptance or compliance testing.
• Wineries and bottling companies verifying stopper cleanliness to prevent wine turbidity, machine clogging or consumer complaints.
• R&D departments assessing new cork treatments or agglomerated cork formulations.
• Procurement and inspection bodies using standardized results for supplier qualification.

Related standards

• ISO 9727 series (other parts cover dimensions, mass/density, humidity, compression recovery, extraction force, liquid tightness).
• ISO 633 (Cork - Vocabulary) - normative reference for terms and definitions.

Keywords: ISO 9727-7:2007, cylindrical cork stoppers, dust content, cork stopper testing, straight cork stoppers, ethanolic solution, membrane filter, physical tests, cork quality control.