Zwartbles have black fleece (grey on older animals) and a very large one at that. It spins okay, not next-to-skin softness but okay for other things. It doesn't felt easily (possibly not at all, I haven't really tried very hard!)
If you are planning on trialling your dogs you may want to make sure they recognise white sheep, horned sheep, and other types of sheep they'll likely meet at trials. (They won't meet many black sheep in trials.
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For spinning and other craft uses, I would have thought Ryeland a better bet, really. You could get some white ones, so the dogs would know about white sheep too
and if your wife would enjoy using the different colours you could get some coloured ones too.
Alternatively, I would have thought you would be able to source mule wethers where you are, and some of them will have nice enough fleeces. (A mule is out of a hill ewe to a Blue-faced Leicester tup.) Mules are nice animals and youngsters are very useful for dog training.