Combining IWTO Certificates

Combination Calculations

Fact sheets illustrating the procedures defined in IWTO-31 for combining Mean Fibre Diameter, CVD and fibre diameter distributions are available in the Fact Sheet section of this site. These fact sheets are also available as a single document.

However, IWTO-31 covers the combination procedures for all certifiable parameters and other parameters that are provided for information. These include

• Wool Base (WB)
• Vegetable Matter Base (VMB)
• Hard Heads (HH)
• Mean Fibre Diameter (MFD)
• Coefficient of Variation of Diameter (CVD)
• Fibre Diameter Distribution (FDD)
• Staple Length (SL)
• Staple Strength (SS)
• Position of Break (POB)
• Colour (X,Y,Z)

Sample Spreadsheets

Two EXCEL spread sheets can be downloaded (use links below) covering all these combination procedures, as well as the procedure for combinations by substraction. The latter is used when a small proportion (less than 5% by weight) is removed from a delivery. The removed component is retested and subtracted from the original combination.

Combinations
Combinations by Subtraction

(right click on these links to download these files)