KiwiGuywrote a review of Sea To Summit Premium Blend Silk/Cotton Sleeping Bag Liner on June 9, 2013
Familiarity: I've used it once or twice and have initial impressions
Well, what do you expect; as with every liner, this is probably the most expensive bit of cloth you will ever buy, but worth while for me.
The liner feels slightly warmer than a regular cotton sheet, however it is significantly lighter and thinner. It is non-stretchy, and the toe has a double seem (forms a box) to accommodate the hight of your feet without wasting any of the length of the liner.
I much prefer this cotton/silk blend to the pure silk liners as I find pure silk a little clingy. I would say this feels like a very fine cotton to the touch, being more matt than silk.
Regarding durability, this would not stand up to anything near what a regular cotton sheet would, however this does make it much lighter and more compact. The material is sufficiently thin that I can feel the texture of the outside of my sleeping pad, however not enough as to leave a pattern on my skin from the pad. It also does not have any kind of zip/button etc to allow you to open it up - it is a fully sewn tube, top entry only. It comes with a nice little zip bag that forms a tube that fits in slightly less than a double palm of the hand. This size will also be able to be compressed by ~30% under weight of other stuff in your pack.
I am a very hot sleeper, and will probably use this without a bag at all down to ~12-15 degrees C. After that, my light summer bag is warm enough down to 5 degrees C for me. I suspect this may add a couple of degrees to that.
In summary, its really expensive for what it is, but it's the best liner I have tried. I would like to try one of the stretchy, moisture wicking liners, but will have to wait for another time. 4 star for the product, but only giving it 3 because it really isn't worth $50.