ISO/PRF 23974-3

ISO/PRF 23974-3, published by ISO, gives guidelines for grading raw red hair sheep skins by mass and size. It is written for people who sort, buy, sell, or inspect these skins and need a common way to describe lot size and weight.

What does ISO/PRF 23974-3 specify?

ISO/PRF 23974-3 specifies how raw red hair sheep skins are presented and graded on the basis of size and mass. The document is organized into five clauses: Scope, Normative references, Terms and definitions, Presentation, and Grading. Clause 5 contains the grading methods, and the document includes two tables for the size and mass categories.

What are the key requirements of ISO/PRF 23974-3?

ISO/PRF 23974-3 sets out a practical grading method that starts with how the skin is prepared, then shows how to measure it, and finally assigns a grade. In practice, this gives processors and buyers a repeatable way to compare skins from different lots.

Presentation before grading

ISO/PRF 23974-3 requires red hair sheep skins to be presented in a defined form before grading. The head is cut straight behind the ears, the shanks are cut off at right angles above the knee and hock, and the tail is cut no more than 40 mm from the butt. This matters because grading only works well when the skins are trimmed consistently.

Size grading and measurement

ISO/PRF 23974-3 grades skins by size using length and area. The skin is folded lengthwise along the backbone line and laid flat, then the length is measured from the root of the tail to the widest point of the front part of the throat, and the width is measured from the midpoint of the backbone line to the end of the belly. Both measurements are taken to the nearest 1 cm with a standard measuring tape, so graders can record the same skin in the same way.

The document then calculates area from the measured length and width and uses Table 1 to assign the size category. Table 1 classifies skins as extra small, small, medium, large, or extra-large. For trade and sorting, this means the size label reflects both the skin's length and its overall spread.

Mass grading and weighing

ISO/PRF 23974-3 also grades skins by mass. Dry salted skins and wet salted skins are unfolded, shaken to remove surplus salt, brushed, and then weighed individually to the nearest 0.1 kg. Raw skins are made free from excess water and weighed to the nearest 0.1 kg. This keeps salt and moisture from distorting the weight category.

Mass categories

ISO/PRF 23974-3 uses Table 2 to classify mass for wet salted, dry salted, and sun-dried skins. The table assigns the same category names across the three preservation states, which helps buyers compare skins even when they have been prepared differently. In practice, a lot can be sorted by the preservation state that matches how it was received.

What terms does ISO/PRF 23974-3 define?

ISO/PRF 23974-3 defines the key skin-condition terms used in grading.

• Dry salted skin - a skin dried in air after treatment with common salt so it can be preserved for a definite period.
• Raw skin - a skin after body heat has dissipated and after trimming, defatting, and cleaning of dung and other foreign material.
• Shanks - the part of the skin covering the leg between the knee and the ankle.
• Sun-dried skin - a skin dried in the sun or in air for preservation for a definite period.
• Wet salted skin - a skin treated with salt to reduce moisture content for preservation for a definite period.

Who uses ISO/PRF 23974-3?

ISO/PRF 23974-3 is used in the leather supply chain by people who handle raw red hair sheep skins. That includes graders, processors, traders, buyers, and quality managers who need to describe size and mass in a consistent way. It is particularly relevant where skins are received, sorted, priced, or recorded for delivery.

What does the ISO/PRF 23974-3 document contain?

ISO/PRF 23974-3 contains the presentation rules, measurement methods, and grading tables needed to classify raw red hair sheep skins. Clause 5.1 gives the length-and-area method for size grading, and Clause 5.2 gives the weighing method for mass grading. The document also includes Table 1 for size classes and Table 2 for mass classes across wet salted, dry salted, and sun-dried skins.

It is a short operational standard rather than a broad theory document. Its main value is that it turns visual sorting into a defined procedure with fixed preparation, measurement, and category names.