Using pre-yarn is a wonderful way to add lines and texture in felting projects. Being 22.5 micron merino wool, it will also felt into open-weave fabrics like margilan silk and cotton scrim. While not a wool roving, one can use it like a very thin pencil roving, and is much finer.
After carding a thin sheet of wool fibre, it is cut into very thin strips, to create pre-yarn, the first structure of a yarn. With no twist in it, there is little strength in the fibre and is quite delicate. Rolls are not necessarily continuous and can vary in thickness.
Pre-yarn is also useful for spinning for beginners or added to other fibres. For ease of use, pull yarn gently from the centre of the ball or ‘cheese’ wheel. Unlike true pencil roving, it’s fragility makes it unsuitable for knitting or crochet techniques.
Also known as wool ‘cheese, this ‘yarn’ is 100% wool and available in balls (minimum 15 gm, +/- 75 m), or a cheese wheel weighing +/-130 gm,
See http://saraquail.com/blog/ for examples of its use in nuno-felt wraps.