This blue dye is so dark it almost looks black.
Sun dyes are sensitive to sunlight. Use diluted dyes (50:50) to paint your background fabric. While the fabric is still wet create a decorative look by placing a variety of flat objects such as leaves, grasses, small pebbles or plastic/cardboard shapes over the top. Place in sunlight and allow to dry. The areas under the objects will not react to the sunlight, thus leaving a ‘negative’ image of the object, while the dye in the uncovered areas will be permanently set.