Overview
ISO 24070-1:2021 specifies a laboratory method to determine the cured thickness (depth of cure) of one‑component building and civil engineering sealants using a taper‑shaped (taper‑wedge) groove test method. The procedure defines specimen preparation, apparatus, conditioning, direct and indirect measurement techniques, calculation of cured thickness and minimum reporting requirements. This standard is used for sealant testing, quality control and product development to quantify how deep a one‑component sealant cures under defined conditions.
Key topics and technical requirements
- Scope: Determines cured thickness of one‑component sealants using a taper‑wedge groove.
- Principle: Fill a taper‑shaped groove with sealant, tool flush, allow cure, then pull the cured strand until the first adhesion of uncured material is observed; measure the cured depth at that point.
- Standard test jig: Linear rectangular taper from 10 mm to 0 mm depth over a minimum length of 300 mm (standard length: 300 mm). Substrate must be dimensionally stable, non‑porous and anti‑adherent (e.g., PTFE or stainless steel with release agent).
- Apparatus and accuracy: Scraper wider than groove by ≥20 mm; thickness calliper with 0.1 mm reading accuracy; ruler with 1 mm accuracy.
- Conditioning and specimens: Condition jig and sealed product 16 h at (23 ± 2) °C and (50 ± 10) % RH. Prepare three specimens, fill from the deepest end, and tool flush.
- Cure and measurement: Cure under defined climate (typically 23 ± 2 °C, 50 ± 10 % RH) for agreed times (commonly 24, 48, 72 h or longer). Two measurement options:
- Direct: Measure cured layer thickness with calliper after removing uncured paste.
- Indirect (calculation): Measure distance W from the top of the groove to the point where uncured adhesion is first observed and calculate cured thickness using the linear taper relation:
cured thickness = (d × W) / L (where d = max groove depth, L = groove length).
- Test report: Must include lab ID, ISO reference, sealant name/type/batch, groove dimensions, climate conditions, cured thickness with cure duration, measurement method and any deviations.
Applications and users
- Manufacturers for product development, formulation optimization and batch quality control.
- Independent test laboratories for performance verification and certification.
- Specifiers, architects and contractors to compare sealant cure depth for application suitability (joint geometry, minimum depth of cure).
- Regulatory and procurement bodies requiring documented test evidence of cure performance.
- R&D teams assessing cure kinetics, tooling procedures and effects of climate on cure depth.
Related standards
- ISO 24070 series (other parts if applicable)
- ISO 6927 - vocabulary for building and civil engineering sealants
Keywords: ISO 24070-1, cured thickness, one-component sealant, depth of cure, taper-shaped groove test, sealant testing, building and civil engineering sealants.