Blogging for Freya: Colors of Cabbage

Red Cabbage is one of the most flexible anthotype dyes I've found yet. You can see above that it has a wide range of potential colors. I've mentioned previously that the dye from red cabbage is extremely reactive to pH changes. I finally decided to do a more extensive test on the subject. So, above, you see various test swatches of red cabbage dye at regular, high and low pH.

The interesting thing is that the dried dye is not strongly reflective of the dye in liquid form. That might mean the dye would function differently on fabric. I recently dyed a silk bag with red cabbage (boiled, not puréed as the dye seen here was) and the result was a medium-deep purple, not the lilac color seen here in the dried dye swatch.

The two swatches labelled "Red Cabbage Juice" are identical: just the mixture of 1/4th head of red cabbage and 300ml of isopropyl alcohol blended until smooth, then filtered through a nylon mesh paint straining bag from Home Depot. That bag, btw, is a GREAT investment for any anthotypist or natural dyer. It washes clean, has a much finer mesh than cheesecloth, and because it's a bag, it's a lot easier to handle than folded cheesecloth. Note that the resulting dye is very watery, but will form a layer of cabbage-residue precipitate at the bottom of its container within an hour or two. It's easy to pour off the majority of the dye into a new container, leaving that mush behind. The liquid dye is bright purple, but dries to a blueish-violet lilac. It can, at higher dilution, dry to an almost periwinkle blue. I'm simply avoiding that dilution at the moment, but I will do more tests on that later!

When a small amount (aprox. 0.25 tsp) of soda ash (sodium carbonate) is added, the pH of the dye goes up, and the purple dye becomes navy blue. The navy blue liquid dries to a soft, pastel blue. If more soda ash is added (another 0.25 tsp), the blue shifts to emerald green. Even more soda ash turns the green yellower, but that yellower green dries the same shade.

Adding acid to the mixture was far less effective, even if it appeared promising to start. I added small amounts of vinegar, which turned the liquid dye bright pink. More vinegar turned the dye a redder pink. Neither vinegar test showed any significant effect on the dry color, though. There may be a slight blue-ing of the purple, but I suspect that's simply because the liquid vinegar diluted the original dye far more than the solid soda ash did. EDIT: 24 hours later, when the swatches were fully dry, I discovered that the acidified red cabbage juice dries as a blue. The original information about vinegar diluting rather that intensifying the color seems to hold true. 

This was a fun experiment, Spiders!