Wendy,
Yes I use procion mx fiber reactive dyes. I do believe, but I could be wrong, that they are the best to use in low water, or cool water applications. And snow or ice definitely qualify.
I purchased Dharma Trading Co.'s colors that mimicked the Spring 2014 Pantone Palette. I used Baby Blue Eyes, Azure, Hyacinth, bougainvillea, watermelon, orange crush, daffodil, sea glass, and probably an amount of Golden Yellow as that's one of my favorites.
I had also mixed my 'own' black by using equal weights of each of those mentioned(not the golden yellow). I was very interested to see just what 'shade' of black I would get. It was ok, but I use it mostly with deconstructed screen printing. Now there's another rabbit hole to drop in on!!
One thing just leads to another in my life. As far as volume of powder to sprinkle? Well, that's a variable. A fun way to see just how much does what is to keep a record. I like taking pictures and writing on my blog about what I'm up to. I have started several 'dyeing journals' and I just can't find the info I want, when I want it. I should probably use a three ring binder so I could group pages by topic. I could use duplicates when it needs to be in more than one place.
Anyhow, I should probably get my blog post done for the day.
Until then, a little more eye candy
Enjoy your day,
Luann