Wool Grades

For centuries, wool has been spun into coarse or fine yams with the wool fiber diameter determining whether it would be coarse or fine. A better classification was needed, however, to describe the difference between wool from the different breeds of sheep, or the wool from the different parts of the same fleece. So, three grading systems evolved over the years to describe different qualities of wool. They are the Blood System, the Count System, and the Micron System.

The Blood System is the oldest system, originating at the time of the early American colonies. It is based on the breed of sheep, and is divided into six grades. The Merino and Rambouillet wool are classified as fine. A half-blood wool comes from sheep that are half Merino or Rambouillet and half another breed. Wool types grown on sheep with fractional quantities of Merino or Rambouillet breeding are called 1/2 blood, 3/8, 1/4, Low 1/4, and Common; and generally, are coarser wool or wool with a larger fiber diameter. The blood system, however, does not describe wool qualities from newer sheep breeds or variations of fleece from different parts of the same animal.

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Type

of

Wool

Old

Blood

Grade

Standard Specifications

USDA

Grade

Range for
Average Fiber
Diameter

Standard

Deviation

Maximum

(microns)

(microns)

Fine

Fine

Finer than 80’s

Under 17.70

3.59

Fine

Fine

80’s

17.70-19.14

4.09

Fine

Fine

70’s

19.15-20.59

4.59

Fine

Fine

64’s

20.60-22.04

5.19

Medium

‘A Blood

62’s

22.05-23.49

5.89

Medium

A Blood

60’s

23.50-24.94

6.49

Medium

3A Blood

58’s

24.95-26.39

7.09

Medium

% Blood

56’s

26.40-27.84

7.59

Medium

/ Blood

54’s

27.85-29.29

8.19

Medium

/ Blood

50’s

29.30-30.99

8.69

Coarse

Lowtf

48’s

31.00-32.69

9.09

Coarse

LowX

46’s

32.70-34.39

9.59

Coarse

Common

44’s

34.40-36.19

10.09

Very Coarse

Braid

40’s

36.20-38.09

10.69

Very Coarse

Braid

36’s

38.10-40.20

11.19

Very Coarse

Braid

Coarser than 36’s

Over 40.20

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