I did some snow dyeing earlier in the spring. I always love the way these turn out. I actually did two sessions, but I tried to capture my method, so some of these pics are from one session, and some are from the other.
I start off by soaking my pre-washed cotton fabric in a soda ash solution. For simplicity’s sake, I mix up 1 Cup of sodium carbonate powder (soda ash) in 1 Gallon of warm water. Some recipes are a little different, but this seems to work just fine and it’s easy. Soak your fabric for 10-15 minutes in the soda ash. This soda ash solution will keep forever, so the leftovers can just be poured back into your container.
Here’s my setup. I have a larger plastic bin, and a plastic-coated mesh basket. In between them, I have some small plastic contains, to lift the mesh bin off the bottom. You want to avoid having your fabric (in the mesh bin) sitting later in the melted snow and dye, or your colors can get muddy. Don’t use metal containers, as they can react with the dyes, and the dye will just rinse off the plastic later. But the containers must never be used for food again.