Paper testing – Stability of paper (ISO 20494)
In addition to RISE paper testing according to ISO 9706 and ISO 11108, where the paper is used for archival documents, there is ISO 20494, which offers paper stability for general graphic applications such as newspapers, brochures etc. Such paper is not intended for archives; instead, it should maintain its durability during normal use and storage.
This service is also relevant in: Metrology, Chemical and biological analysis
Service details
- Service
- Paper testing – Stability of paper for general graphic applications (ISO 20494)
- Delivery level
- Accredited
- Standards
ISO 20494 Paper — Requirements for stability for general graphic applications
ISO 1974, Paper — Determination of tearing resistance — Elmendorf method
ISO 5630-3, Paper and board — Accelerated ageing — Part 3: Moist heat treatment at 80 degrees C and 65 % relative humidity
ISO 6588-1, Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction
ISO 10716, Paper and board — Determination of alkali reserve
- Price
Contact RISE for price information. Please find the contact information below.
Purpose
Paper that meets the requirements of ISO 20494 shows stability for general graphic applications. Examples of possible end products with this paper include newspapers, brochures, catalogs, books, office prints, etc.
The ISO 20494 standard is based on providing a paper where mechanical fibers and/or recycled fibers can be used in paper products, thereby reducing production costs while promoting sustainability and contributing to a significantly reduced environmental footprint.
Method
pH - Cold Water Extract
Acidic paper deteriorates quickly, so pH is an important parameter to measure in paper. Electrolytes are extracted from the paper in a water solution, and the pH value is then measured on this cold water extract.
Alkali Reserve
The formation of acids from air pollution in the surrounding air or natural ageing is harmful to the paper. Therefore, such paper usually contains some alkaline filler (e.g., calcium carbonate) to prevent acid attacks and neutralize the harmful acids, i.e., the paper has an alkali reserve. The alkali reserve can be measured through a titration process.
Tear Strength
Tear strength is a measure of the paper’s mechanical strength and indicates the force (mN) required to tear a piece of paper. Preserving tear strength after ageing is a measure of the paper’s ability to remain durable in the future.
Requirements according to ISO 20494
- Tear Strength: The tear strength has a minimum value based on the paper’s surface weight.
- Preservation of Tear Strength: The tear strength must not decrease by more than 80% after 12 days of aging at 80°C and 65% RH.
- pH Cold Extract: Between 7.5 - 10.0.
- Alkali Reserve: At least 0.8 mol of acid per kg.
Accreditation
The testing for paper stability maintain high quality through accreditation according to SS-EN ISO/IEC 17025:2018.
Delivery
Testing report from an accredited laboratory.