Overview
EN ISO 4119:1996 - Pulps: Determination of stock concentration specifies a laboratory method for measuring the stock concentration of aqueous pulp suspensions. This International Standard (second edition, revising the 1978 edition) is intended for use in laboratory procedures that underpin many other pulp test methods and quality-control routines. It is applicable in principle to all kinds of aqueous pulp suspensions but is not intended for determining the saleable mass of slush pulps.
Key Topics
- Scope and purpose: Defines the test objective - the ratio of oven-dry mass of material that can be filtered from a sample to the mass of the unfiltered sample, expressed as % (m/m).
- Definitions: Clarifies terms such as "stock" (aqueous suspension of pulps which may contain fillers/additives) and "stock concentration".
- Apparatus and accuracy: Typical laboratory apparatus includes:
- weighing containers and balances (100–500 g range and precision requirements);
- filtering device (Büchner funnel, diameter 90–150 mm) and circular filter paper that retains visible fibres and inorganic material;
- drying oven (105 °C ± 2 °C) or hotplate (150 °C ± 15 °C) and means for drying to constant mass.
- Sampling and sample preparation: Emphasises thorough mixing and scooping removal to minimize fibre separation; recommended sample sizes and dilution guidance when concentration exceeds specified limits.
- Procedure and calculation: Filter a measured sample, dry filter paper and fibre mat to constant mass, and calculate stock concentration as the oven-dry mass filtered divided by the initial sample mass. Weighings are carried out to a defined precision and results reported to two decimal places.
- Reporting: The test report should reference the standard, identify the sample, state the stock concentration (% m/m), and document any deviations or unusual observations.
Applications
EN ISO 4119:1996 is valuable for laboratories and production facilities that need:
- consistent and reproducible stock concentration measurements for pulp process control;
- a validated basis for subsequent pulp property tests that depend on known suspension concentration;
- improved quality assurance in pulp and paper testing by standardising sampling, filtration and drying practices.
Practical benefits include reducing variability in downstream tests, supporting repeatable sampling and enabling reliable comparisons between laboratories.
Related Standards
- The standard was prepared by ISO/TC 6 (Paper, board and pulps), Subcommittee SC 5 (test methods and quality specifications for pulp).
- EN ISO 4119 is referenced by a range of other ISO standards dealing with pulp suspensions and laboratory test methods. Laboratories should consult relevant ISO test-method documents for related procedures and cross-references.
Keywords: EN ISO 4119:1996, pulp, stock concentration, aqueous pulp suspensions, sampling, filtration, oven-dry, laboratory method, quality control.
