Experiment

Instead of pouring out the pickled red cabbage juice when the jar was finished, I kept it.
Then when i was getting tired of the vinegar smell in my room....hmmm.
I put in some scraps of silk habotai that had some marking from an indigo dip.
I nuked it for 2min.

Drained it and voila! fuchsia and purple

Then I put it in the washer on a rinse cycle. To be honest, almost everything I try for an experiment comes out that colour. So I didn't really need more! But it was silk, so I could work with that.

Result:the reddish part of the purple washed out leaving a light periwinkle blue! Yes, I like this.
In true life, you hardly see the indigo markings and the silk has a lovely sheen. But the camera picks up the darker greenish blue of the indigo.

I have saved the rest for more experimenting.
my understanding of the science: Natural dyes are mostly fugitive, meaning they will fade. If you use a mordant, it is more likely to last longer. Because the pickled cabbage juice had vinegar, the vinegar works well on the silk and it will (should) retain colour.

I like experiments that come out better than you thought it could.