Wool Blend

Wool Blend or Blends is a subject of great importance to designers apparel manufacturers and carpet makers.

The unique character of wool as a natural fibre is highlighted by the many different types and commercial end uses. There are four main characteristics I would talk about in wool.

1. Micron count or Fibre diameter.
2. Staple length.
3. Crimp.
4. Fleece density or bulk.

Micron count or Fibre diameter.

There are a multitude of uses for wool & wool blends, pure wool products as in apparel, carpets & curtaining are made with a Wool Blend. This does not mean to say they are not pure 100% wool.

This comes about through the many different sheep breeds most of them producing their own particular type of wool suitable for a different purposes.

Probably the best known wool breed would be the Merino. A good section of the general public would be aware that Merino wool is very fine and soft. The great Marketing Job being done by Ice Breaker of New Zealand can take some credit for this.

Merino wool has always been highly sort after by Italian Wool spinners for very expensive pure wool suits.

Wool is measured by its fibre diameter or fineness, a Micron measurement. At one end of the scale we have the Superfine Merino at 12micron plus and the other end the Drysdale or the Scottish Blackface with a fibre diameter of up to 40 micron.

A common wool blend is fine wool ( not always Merino ) and nylon or polyester. You will buy this in socks and outer wear. The fine wool giving a nice handle and the nylon or polyester giving longer wear ability. A wool blend involving Merino wool with feral possum fur, the "Possum Mink", now very popular and very expensive.

Another prime example of a wool blend is the carpet wool yarn. A major export earner for New Zealand this is a blend of the coarser end of cross bred wool with about 10 to 15% of Drysdale or Scottish Blackface.

Why this mix you may ask. To further complicate the different properties of wool, these two latter breeds have about 40% of their fleece as Medulated Fibre. "Normal "wool fibre as you may note in the photo is a solid fibre with outer " scales" These scales trap air around the fibre and add to its insulating qualities. They also absorb moisture which is why wool is now popular in sports and other outdoor clothing. Medulated fibres are hollow, have no scales and add a lot of resilience to a yarn. Important in carpet yarns to prevent the carpet pile collapsing under furniture.

Picking the right wool blend for the job is more of a science than you would imagine.

Staple Length.

You will note from the photo the significant difference in Staple length between the Merino & the Romney breeds. Both examples are 12 months growth.

The longer staple of the Romney & other coarse wool breeds is ideal for spinning into carpet yarns and the like. However these same wools if too short as a result of being shorn earlier. or from the legs & belly of the sheep are dificult and result in lower recovery percentages in the spinning process. A wool blend of both short & long fibres overcomes some of this problem.

The Shorter fine wools don't present the same problem as the fibres tend to hang together much better through out the processing.

Crimp

The Crimp in a fleece is what gives the yarn its elasticity. Great in garments for comfort, not so desirable in a carpet wool blend. There was at one time a measurement factor of "crimps per inch " which is no longer common. Merino would have a measurement of up to 15 crimps per inch as against Romney with 4 or 5 and Drysdale with none at all. Crimp is a factor which varies considerably between breeds. Crimp in the length of the fibre determines its elasticity. In apparel incorporating this type of wool in a wool blend can be quite an advantage. Definitely not in a wool blend for carpets where it is important for the pile to stay rigid.

Fibre Density or Bulk.

An important characteristic again in the manufacturing process.

All wool is scoured or washed as a first stage prior to the spinning process. There is always a percentage of wool lost, short broken fibres dirt and of course the natural wool grease. The wool grease is recovered and processed into lanolin

This difference between what a manufacturer buys in weight and what he finishes up with after processing is calculated as " yield ". e.g. If he buys a 1000 kgs of raw wool and finishes up with 1000 kg of yarn his "yield "would be 100%. This never happens. Typically after washing the Yield may be 60/70%, after carding & spinning the yield may again be around 70% of the scoured weight or less. A good dense fleece as in say the Perendale or Southdown will generally yield well in the spinning process but may lose more weight during scouring.

All these factors must be considered by the buyer when putting together a good wool blend.

We farmed 5000 Drysdales bred principally for wool used as a wool blend with Romney. The value of the Drysdale wool in a wool blend was its pure white colour, strong micron count, 40 micron and the percentage of medulated fibres. This made it a very tough fibre.

Ideal for carpet and upholstery but because of its open nature, not particularly dense, it had to be used in a wool blend to increase the yields through processing.

New Zealand has always been noted for its Cross bred wool. This is wool in the Mid Micron range 20 to 28 micron. here a number of breeds that produce this type of wool but again some of them have quite different characteristics.

The Cheviot & the Romney.

While farming we developed a wool blend using our own Drysdale sheep and Romney Crossbred Fleece for a coarse yarn which we had manufactured into Curtaining Material. We sold this material both for pure wool curtaining and also upholstery. Great Insulation and the upholstery material wore extremely well and looked great.

There are a number of commercial & practical reasons why wool blends using other fibres have been developed. One of course is cost. Synthetic fibres are able to be produced much cheaper and are more consistent as to type. They do use oil which is a non-renewable resourse and to my mind not particularly environmentally friendly

However I have written this article mainly to inform of the wool blend articles & uses just using the different wool types.

Wool blends with synthetic & other fibres is worthy of an article on its own.