I recently took a Nuno felting class with Magi Shapiro at the Cultural Arts Center of Glen Allen http://www.artsglenallen.com/ Though I am familiar with almost all the steps of this felting process, I wanted to gain some hands-on experience with the guidance of a teacher. Magi also teaches wet felting and owns a herd of Icelandic sheep!
We first learned how to make all-wool felt, but most of us were itching to start Nuno felting. This type of felting uses a light-weight fabric, most often silk, but you can use rayon, as a base on which to lightly apply and felt wool. First, I laid out my design on the silk scarf, then lightly needled into place anything I did not want to move during the wet felting process.
Next, the scarf is gently laid on a long piece of bubble wrap, then covered with a piece of nylon curtain fabric (I have used netting instead with good results). The entire scarf is then wetted with warm water into which a squirt of dish soap has been added (about 1 gallon of warm water to that squirt of soap: I often use a gelled mixture of olive oil bar soap instead). Maggie has cool bulb sprayers, but you can use a spray bottle or saturated sponge. Then, the entire thing, scarf, nylon and bubble wrap is rolled around a tube of some sort; we used cut up pool noodles (flotation devices), but for smaller pieces I have used a rolling pin that I wrapped in plastic). The whole roll is tied together with old stockings (hosiery) then rolled 100 times, back and forth, across a towel.
The roll is then unrolled and the wool checked for felting- you take a light pinch of the wool and see if it has adhered to the silk. I then rolled it back up and rolled it 200 more times, checking at the halfway point (my guess is you will need to do this at least 300 times, but, using the wrists to roll, it is not difficult and does not take a long time).
After unrolling the scarf, we then scrunched it up, as shown here:
..and this is ruched: see the puckers in the silk fabric? That is what you want. You can throw some more and get more ruching, but I was finis!
Close up of ruching:
After the scarf is done, rinse it in a basin of tepid water to which a half cup of white vinegar has been added to remove and neutralize the soap and dry it flat. If you need to ever wash it, wash it in cold water with gentle soap.
And here is the final scarf! It lost about 20% of its length as the wool felted to the base. Not bad for a first time using silk...onward and upward!
PS "Ruching" is better defined as pleating, and maybe "puckering" is more accurate?