Hi Vick
Why should sharps tangle in fleece or knits? No-one has ever given me a good **technical** explanation of this, so I suspect it is a myth. I have seen 'explanation' which focus on the way that a sharp can go through a single thread while a ball-point is more likely to push it aside. However, what this has to do with fleece is beyond me.
Especially as I have sewn a lot of fleece, synthetic and Lycra with stock sharps, without problems.
Rasant is made by Amann & Sohne GmbH of Bonningham, Germany. It is a professional thread, dearer than Guterman, but in my experience better. I note that our local sewing shop does stock Rasant for pro use. They do not advertise this: you have to ask.
> the problem is that it is a cotton-wrapped polyester.
That is is, but there is a reason for this. When sewing at high speeds the passage of the thread through the needle and the needle through the synthetic fabric heats the tip of the needle. If you do this with a pure synthetic thread the needle can get hot enough to cause melting of the individual fibres in the thread – which is a short cut to disaster. The *real* reason pro threads are core-spun poly-cotton is to sheathe the thread in cotton fibres to protect the polyester core from the high temperature of the needle.
True, the average home sewer making little things is unlikely to run into this problem: they are usually sewing far too slowly and for short runs. That's fine.
Is Guterman stronger than Amann Rasant? I have tested this myself, and when matching the threads for size I find Rasant stronger. Amann Serafil is slightly stronger again, but that is a pure synthetic and can have serious problems with tangles.
Cheers