Overview
ISO 11527:2018 - Buildings and civil engineering works - Sealants - Test method for the determination of stringiness - defines a laboratory method to measure the stringiness (maximum strand length) of a wet-applied one‑component sealant. The test quantifies the length of a strand that can be pulled from a freshly applied sealant using a probe and a constant traverse rate, reporting the maximum travel (Lmax) in millimetres.
Key topics and technical requirements
- Scope: Wet-applied one-component sealants; measurement of stringiness (strand length at break).
- Principle: A probe (tip) is submerged into the sealant, held for 2–10 s, then withdrawn at a constant rate until the string breaks; the maximum travel is recorded.
- Apparatus:
- Extension device or universal testing machine with traverse-rate control better than ±1%.
- Two probe options: Tip 1 (round, aluminium, radius R = 7.5 mm) and Tip 2 (conical, polyethylene).
- Container: minimum 30 mm depth and diameter.
- Test conditions:
- Conditioning: sealant shelf-aged ≥1 day; store samples, container and probe at (23 ± 2) °C for ≥6 h.
- Test ambient: (23 ± 2) °C, 50 ± 10% RH.
- Submersion depth: minimum 10 mm.
- Traverse (pull) rates: 700 mm/min or 500 mm/min (agreed between parties).
- Procedures:
- Two methods depending on skin-over time:
- Method A (slower curing, skin-over ≳10 min): 4 sequential pulls per specimen, discard first, 3 specimens → nine reportable readings.
- Method B (faster curing, skin-over ≲10 min): 2 sequential pulls per specimen, discard first, 9 specimens → nine reportable readings.
- Do not clean tip between sequential pulls on the same specimen.
- Results & quality:
- Report individual Lij, specimen averages, and total average Lave,max to the nearest millimetre.
- Repeatability limit: expected maximum difference between two independent results should not exceed 5 mm at 95% confidence; if unacceptable, report individual values and note “insufficient reproducibility of results.”
- Test report must include tip type, depth of submersion, traverse rate, measurement method, individual and average values, sealant identification and any deviations.
Applications and users
- Practical for manufacturers, R&D, and quality-control laboratories evaluating sealant workability and application behaviour.
- Useful to product specifiers, architects, façade and glazing engineers, and certification bodies when comparing sealants or verifying conformity to performance requirements.
- Helps in product development (tooling and flow characteristics), batch control, and tender/specification compliance checks.
Related standards
- ISO 6927 (sealant vocabulary) - referenced for terms and definitions.
- ISO 5725‑1 and ISO 3534 (statistics and repeatability) - referenced for precision and reporting guidance.
Keywords: ISO 11527:2018, stringiness test, sealants, one‑component sealant, universal testing machine, probe tip, traverse rate, skin‑over time, sealant testing.