Overview
ISO 1652:2011 - "Rubber latex - Determination of apparent viscosity by the Brookfield test method" specifies a standardized procedure to measure the apparent viscosity of natural and synthetic rubber latices using a Brookfield-type rotational viscometer. The method applies to Hevea and non‑Hevea natural latices, latex concentrates and compounded latices. The standard covers sampling references, sample preparation (including dilution to a specified total‑solids content), test conditions and reporting requirements.
Key keywords: ISO 1652:2011, rubber latex viscosity, Brookfield method, apparent viscosity, viscometer, latex testing, total solids.
Key topics and technical requirements
- Test principle: Torque on a rotating spindle immersed in latex is read on a scale and converted to apparent viscosity using spindle/ speed-dependent factors.
- Equipment: Manual Brookfield-type viscometer (L or R instruments) with specified spindles and removable guard; glass beaker (≥85 mm internal diameter, ~600 cm³); temperature-controlled water bath.
- Speeds and spindles: Standard rotational frequencies specified for the two instrument types (L and R). Spindle selection is important to keep readings in the preferred range (about 10–90 scale units).
- Conversion factors: Scale readings are converted to mPa·s (cP) using factors given in the standard (examples: L1 ×1; L2 or R1 ×5; L3 or R2 ×20; R3 ×50).
- Temperature control: Tests performed at 23 °C ±2 °C (or 27 °C ±2 °C in tropical climates); precise test temperature must be recorded.
- Sample preparation: Total solids determined per ISO 124; dilute with high-purity water where required; remove occluded air by standing or vacuum (procedures vary with viscosity).
- Precision and validation: Annex B reports precision from an interlaboratory study (repeatability/reproducibility); users should apply these data appropriately.
- Reporting: Test report must reference ISO 1652, include sample ID, instrument and spindle used, solids content, temperature, result units, and any deviations.
Applications and users
- Quality control and incoming inspection in rubber manufacturing (latex concentrate producers, glove and dipped goods manufacturers).
- R&D and formulation labs evaluating rheological behavior of natural or synthetic latices and additives.
- Laboratories performing comparative studies, process monitoring, or supplier qualification.
- Regulatory and standards bodies needing reproducible viscosity data for specifications.
Practical value: standardized Brookfield testing gives consistent, comparable apparent-viscosity measurements for process control, product specification and R&D comparisons.
Related standards
- ISO 123 - Rubber latex - Sampling
- ISO 124 - Latex, rubber - Determination of total solids content
- ISO 2555, ISO 3219 - Related viscosity test methods for polymers and emulsions
Using ISO 1652:2011 helps ensure reproducible latex viscosity data for manufacturing control, specification compliance and technical assessment.
