Barley – Chapter 6 | Official Grain Grading Guide

Determination of commercially clean

All samples must be analyzed to determine if they are commercially clean prior to dockage assessment. The analysis of samples, that are clearly not commercially clean, may consist of a visual assessment. For example, if there is no doubt that a sample contains more than 0.1% of small seeds without passing the sample over the Carter dockage tester as set up below and weighing the small seeds, then primary dockage assessment procedures can be followed. Where there is any doubt regarding whether the sample is commercially clean, the sample must be analysed using the procedures outlined in steps 1 through 7 below to confirm that the sample is not commercially clean prior to assessing a dockage.

1. Using a Boerner-type divider, divide the sample to obtain a representative portion.

  • Official samples shall be at least 1 kg.
  • Unofficial samples shall be at least 1 kg.
2. Pass the sample over the Carter dockage tester set up as follows:
Feed control 5
Air control 3
Riddle None
Top sieve No. 4.5 round-hole
Centre sieve Blank tray
Bottom sieve None
Sieve cleaner control Off

3. Small seeds passing through the No. 4.5 round-hole sieve are weighed and the percentage calculated to determine if they meet the commercially clean specification of the grade for small seeds. (Column #1 in the Barley Export grade determinant table)

4. The sample portion passing over the 4.5 round-hole sieve is divided using a Boerner-type divider to a representative portion of not less than 250 grams

5. The portion divided from step 4 is handpicked to remove roughage (as defined in the Glossary)

6. Roughage is weighed and the percentage is calculated

7. All material passing through the No. 4.5 round-hole sieve is combined with dust and chaff removed by aspiration and handpicked roughage material are added together to determine if they meet the commercially clean specification of the grade for Total small seeds, attrition, dust, chaff and roughage. (Column #2 in the Barley Export grade determinant table)

Should the percentage concentration of either of the factors determined in steps 1 through 7 exceed the specifications set out in columns 1 or 2 of the barley export grade determinant table, the sample will be considered to be not commercially clean. Dockage will be assessed on samples determined to be not commercially clean by following the procedures defined under Determination of dockage.