After washing, drying and ironing the pieces from the previous day, I held each piece up by the top and bunched them in a roughly gathered fashion (eg not folded), then wound them loosely into a ball like a pinwheel. Then I once again placed them in a plastic bag, this time adding a cup of soda ash to each bag and ensuring the fabric was dampened through. Then I put them in the freezer overnight. Here they are when I removed them the next day.
This time, I just squirted a quantity of dye over the outside of the frozen ball - Navy for the blue one, and Warm Black for the brown one. Then I batched them and washed them in the normal way. These are the results - I like the brown one better as there's more contrast. My conclusion? A lot more time-consuming, and I can probably get much the same result without ice, but fun to play around with , particularly the over-dyeing.
It was all too much for Seven, who had to go and have a rest out on the deck.