I usually print botanical colours by making a cornstarch thickener on paper, and an indulca thickener on fabric. Cornflour is a safer and a more readily available ingredient that indulca. I want to test how well cornflour botanical pastes will print onto fabric.
I simmered the outer leaves of red cabbage for 30 minutes, and left to cool in the dye liquor. Next I strained the mixture through muslin, and then thickened it with cornstarch; approximately 8 g for every 100 g liquid.
I used common kitchen ingredients as modifiers; lemon juice for an acid, and baking powder for an alkali.
I steamed the prints to fix them, using an adapted burco-boiler. Steaming at home can also be done using a large pan of water.
To allow for comparisons, I screen-printed the three different red-cabbage colours onto a range of pre-mordanted fabric, and onto paper. Cotton and silk with soya mordant (kitchen safe), silk and wool with alum mordant (use with care), and leather with iron-water (use with care).
When I contrast these prints with previous research, I can see that the colour yield of indulca based thickener onto fabrics is better than the colour yield of cornflour.
In conclusion I continue to prefer cornflour on paper, and indulca on fabric.