Silk noil is made with silk yarns created from very short fibers – usually remnants from other cloth manufacture. The yarn has a rougher texture and is less reflective than longer-yarn silk, which results in a fabric similarly dull and somewhat rough underhand.
Noil is more brittle than silk made with regular yarns, and so it can have a shorter functional life. Nor does it drape as well as other silks. For all that, I really like it. The texture is very interesting and the fact that it’s a natural fiber makes it more comfortable to wear than its synthetic counterparts. The stiffer body makes it seem more ‘rugged’ which means it’s not just for rich/noble characters. I’ve seen noil used for costumes all across the spectrum from dressed-up barbarians to anime characters and beyond. If there isn’t a whole lot of it in your average Black Watch rig (Game of Thrones) I’ll eat my hat. Ditto half of the secondary characters in the Lord of the Rings films.
I used silk noil to make a big black cape for a spooky character and it looked fab. Visually more interesting than wool broadcloth and a lot more comfy to wear in overheated hotels.
For silk, it’s quite cheap. You can find it for as little as $6/yd at Dharma Trading, albeit only in black and white. More typically it’ll be $10 – $20/yd, the variance depends on the weight of the fabric, the color and how over-reaching the seller happens to be. It’s most often sold in a plain weave, but I’ve seen dobby-woven noil for sale online.
You can use a regular or Microtex needle for sewing silk, with all-purpose thread. Since it has a rougher texture than other silks, you don’t have to worry about it slipping all over the place when being cut and sewn, but you might have some issues with fraying. Check out How to Handle Fray-Happy Fabric for further advice.