ISO 9885:1991

Overview

ISO 9885:1991 defines standard test methods for determining the deviation from flatness of the top sealing surface of wide‑mouth glass containers (e.g., preserving jars) where a hermetic seal is required. The standard specifies two complementary approaches - a rapid attribute quick check and a quantitative measurement - and describes the principle, required apparatus, sampling, test procedure, how results are expressed, and the contents of the test report.

Key topics and requirements

• Scope: Applies to wide‑mouth glass containers intended for sterilization and other uses requiring a hermetic seal.
• Two test methods:
  • Quick check (attribute): Use a feeler gauge of the permitted out‑of‑flatness thickness and attempt insertion between the finish and a horizontal baseplate around the circumference. If the gauge cannot be inserted, the container passes.
  • Determination (quantitative): Measure the distance between the top sealing surface and a flat plate pressed onto it using feeler gauges to identify the smallest gauge that fits. Terminate when two successive gauges differ by no more than one step (typically 0.05 mm).
• Apparatus: Minimum required equipment includes a horizontal flat baseplate and feeler gauges (recommended in steps of 0.05 mm; examples 0.05 mm, 0.1 mm). The standard notes alternative automatic inspection devices (e.g., vacuum tests) may be used for high‑speed checking.
• Sampling: Sample size is to be agreed between parties - the standard does not mandate a single sampling plan.
• Reporting: Test report must reference ISO 9885, list the method(s) used, sample size and container type, manufacturing details, apparatus, results, and tester’s name/signature and date.

Practical applications

• Ensuring consistent sealing performance of preserving jars and other wide‑mouth containers used in food, pharmaceutical, and sterilized consumer products.
• Quality control and acceptance testing during glass container production or incoming inspection.
• Verifying compliance with contractual flatness tolerances to prevent leakage or compromised sterilization.
• Integrating into production QA protocols or third‑party inspection reports.

Who should use this standard

• Glass container manufacturers and process engineers
• Packaging and product development teams (food, pharma)
• Quality assurance / inspection laboratories and inspectors
• Purchasing and compliance officers responsible for supplier acceptance criteria

Related standards

• ISO 9009:1991 - Glass containers: Height and non‑parallelism of finish with reference to container base - Test methods (distinct but related dimensional requirement).
• ISO 7348:1991 - Glass containers: Vocabulary (definitions used by ISO 9885).

Keywords: ISO 9885, wide‑mouth glass containers, deviation from flatness, top sealing surface, test methods, feeler gauges, flat baseplate, hermetic seal, container inspection.