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.
Open preview (PDF)Wide-mouth glass containers — Deviation from flatness of top sealing surface — Test methods
