Below, I have got some fabric laid out on top of parchment. I would not use newspaper for this process, because the process involves wetting and the newsprint might transfer, or even wors, stick to the fabric when drying. (ask me how I know) The box of pastels at the top is a pack of windsor and newton and is there as a reminder to me to explain a few things.
My second point is that I usually add pastels as a powder and because they are mostly pigment, they are very bright even if only a little is added. When colouring fabric, the less you have to add, the less it will alter the hand of the fabric and unless you add a lot of pastel, the hand is pretty much the same.
I couldn't wait to finish, so I ironed the fabric dry. Because there is little other than pigment, ironing doesn't really alter the effect like it does with some fabric paints.
And here are some high res pictures of the finished fabric.
rotating stencil brush
small strokes with brush
smearing with fingers
As you see it is very easy to get very vibrant colours with this technique. And there are more ways than these to use them.
That is for another lesson.
It really is worth experimenting with this technique. I would love to see some of your results.
In Art, there is no such thing as a failed experiment, only experiments with interesting results.