Another interesting technique from India Flint's book "Eco Colour" is what she calls "ice-flowers". This involves the collection of purple and deep red flower petals (which contain anthocyanins), which are then frozen in plastic containers or sealed plastic freezer bags for at least two days. Following India's instructions, I collected the dead-heads from purple violas over a period of several weeks and froze each batch of flower heads as soon as I had collected them, adding them to the plastic bag in the freezer. When I was ready to use them, I tied a handful of frozen flower heads into a muslin bag, immersed this bag in lukewarm water and squeezed it to extract the colour. The liquid soon became a rich purple colour and I removed the bag with the flowers and then stirred a teaspoonful of alum sulphate into the solution. (I added alum because the materials I intended to dye had not been mordanted. Next time I try this method I'll make sure I have some pre-mordanted fibres ready to use.) I then put some cotton and silk fibres into the liquid and left them to steep overnight. More colour variations are possible if other substances, such as an acid or an alkali, are added to the solution, so I still have much scope for experimentation. (I later added a wool skein to the exhaust dye bath and this became an attractive light leafy green.)
The photos below show, from the top: the frozen viola flowers ready for colour extraction, the dyed materials (silk on the left and cotton on the right)), a closer view of the dyed silk fabric, and finally a closer view of the dyed cotton fabric. The dyed skein is cotton and the dyed cotton fabric is the bag in which the flowers were tied. The attractive variegated colour effects on this bag are probably the result of the flowers being pressed against the fabric. As with the leaf prints, I must test these ice-flower dyes for light- and wash-fastness, once the colours have had time to mature.