Thursday, 10 July 2014

What happens to wool samples in the lab? Part 1

This year I have continued collecting sheep wool samples from Scandinavia and the Baltic region. I am very grateful to the farmers who have sent me samples from their sheep, which are all from heritage breeds. These sheep have eaten grass and hay but no concentrates. 

I thought I would show you what happens to the samples once they get to the laboratory:

Sample logging
First the sample is logged. Sample logging is boring but essential. Each sample is allocated a number in our central database, and that number is also written on the sample bag, so we can always find out what it is and where it came from.

Preparation for washing
A small section of each piece of fleece is transferred to a small glass vial. The sample number is also written on this vial. These samples are from Estonia: double coated fleeces in a variety of colours. The remainder of the sample is kept in a fridge.

Wash number 1
Each vial is filled with water, capped, and put into the machine on the right, which is a sonicator. This shakes its contents using ultrasonic waves, which helps dissolve the muck on the wool. I sonicate with water to remove dirt, and then with hydrocarbon solvents to remove grease from the fibres. I use 6 separate washes, which is more than most researchers use for cleaning hair for isotope analysis. I found that wool needs lots of cleaning (much more than, say, cattle or human hair) as the fine fibres trap much more muck between them than do coarser fibres.

Next: grinding the wool into powder in Part 2.