Dyeing art

I've been creating some vegetable dyes to test their vibrancy and to simply experiment with the process.  I have red cabbage, onions and red cabbage.

Mordants 

To fix my dyes to my chosen material, I need a mordant.

I have questions about the chemicals that are suggested on websites explaining the dyeing process. How is Alum manufactured? It's chemical name is hydrated potassium aluminium sulfate.  Who makes this and where?  Is it poisonous?  Is it natural? Where do I buy it from? Can I make it myself?  What are the true costs of this product - environmentally?  

I used iron as my mordant. The only iron I could see were some hideous iron capsules that I was never going to take. 

I cut some samples of the garden twine that I had found in the shed and seeped it in some hot boiled water with the iron powder.  Next I poured some of each of the liquids into 3 separate containers.  I then added the twine samples to the liquids, pushing them in deep and immersing them thoroughly.  

I repeated this but on the second attempt, I boiled the twine in the water with the iron powder for longer before immersing it in the dye liquids.

The bottom row is the first attempt and the middle row is the second. Above left is the original ball of twine, uncoloured and next to it is a sample of twine boiled in iron water.

The left bundles on the two rows are dipped in red cabbage, the middle one is yellow onion dye and the right bundles are red beetroot.

The first attempt at red beetroot didn't really take, except in very small patches.

I enjoyed trying this dyeing process and needed to be aware of a scientific approach to the testing, making sure to only change one variable at a time to establish what worked well and why. It was satisfying to create my own colours from natural ingredients, except for the iron tablet and I was pleased with the results.  

I did this just for the fun of experimenting and research. I might need this one day. It was something I wanted to explore as a possible fibre to use in the habitat project that has sustainability as a core theme.