ISO 2550:1972

Overview

ISO 2550:1972 is an international standard established by the International Organization for Standardization (ISO) that focuses on hand-made textile floor coverings, specifically carpets. This standard provides a clear method for determining and identifying the different types of knots used in manufacturing hand-made carpets. Primarily, it addresses knots tied by finger or by hook and offers a visual identification technique to recognize knot types. This standard is essential for textile manufacturers, carpet appraisers, quality control professionals, and researchers involved in the carpet industry.

Key Topics

• Types of Knots in Hand-Made Carpets
  ISO 2550:1972 describes the most common knot types including:

  • Persian knots (Sehna or Sinneh knots): These knots can be tied from left to right or right to left depending on the number of weft threads between rows, with specific formation variations.
  • Turkish knots (Gordes, Tabriz, or Izmir knots): Typically formed over two or more warp threads with multiple weft threads separating knot rows.
  • Double knots: Detailed variations of double knot formations to enhance carpet strength and design complexity.

• Visual Identification Method
  The standard prescribes a step-by-step procedure for identifying knot types:

  • Bending the carpet face outward to expose tuft bases.
  • Separating the pile between rows of tufts to reveal the knot structure.
  • Careful examination, possibly with a magnifying glass, to determine the knot type and count the weft threads separating rows.

• Reporting Requirements
  Detailed reporting guidelines include:

  • Confirmation that knot identification follows ISO 2550.
  • Documentation of any deviations from the standard.
  • Identification of knot type, corresponding name, number of weft threads, and reference to the applicable figures from the standard.

Applications

ISO 2550:1972 is directly applicable to industries and professionals involved in:

• Carpet Manufacturing: Enabling consistent identification of knot types to maintain quality standards and enhance production accuracy.
• Textile Quality Control: Facilitating standardized evaluation of hand-crafted carpets in both factory inspections and final product certification.
• Appraisal and Authentication: Assisting expert evaluators in authenticating carpets by identifying knot types, which can impact value and origin classification.
• Educational and Research Institutions: Providing a reliable reference for teaching and studying textile craftsmanship related to carpet knotting techniques.

Related Standards

• ISO/TC 38 - Textiles: The technical committee responsible for this standard produces additional documents related to textile testing and classification.
• ISO 2424 - Textile floor coverings - Vocabulary: Offers terminology that may complement knot type identification and carpet manufacturing standards.
• ISO 12507 - Textile floor coverings - Determination of pile thickness and height: Relevant for complete assessment of hand-made carpets alongside knot type analysis.

By adhering to ISO 2550:1972, industry stakeholders ensure standardized identification of carpet knots, which is critical for quality assurance, product classification, and maintaining heritage techniques in hand-made carpet production. This supports the global marketplace in promoting trust and transparency through recognized textile flooring standards.