This has been a kind of holy grail for some dyers. Can we paint or print indigo directly onto cloth and make it adhere as a dye rather than a pigment? Until recently it was thought to be somewhere between extremely difficult and impossible.
In my latest studies of contemporary and old-is-new-again techniques, I found descriptions of two methods of direct application of indigo to cellulose fiber textiles. One, an older industrial process, requires more caution and effort in working with caustic chemicals and multiple steps to steaming the final product. The second is simple and non-toxic. This is the one I had to try.
Method 1, found in Joy Boutrup and Catherine Ellis’ book The Art and Science of Natural Dyes, gives recipes and procedural methods for old-fashioned printing with indigo. Their recipe calls for an alkaline print paste containing indigo and lye to be applied to a sugar-coated textile, which is then steamed to reduce the indigo. Read all about it and follow the instructions in the book!
Method 2 can be found in Michel Garcia’s latest Natural Dye Workshop video No. 4: Beyond Mordants, wherein M. Garcia demonstrates a technique inspired by “spherification“, a technique of molecular gastronomy. I am not spilling many beans here because his demonstration is deliberately vague on measurements and quantities, meaning that if we wish to duplicate his process, we will need to do a lot of trial and error experimentation. No problem – this is what I live for!
In this simple and non-toxic method, indigo is mixed with sodium alginate, a common thickener and print paste ingredient, then applied to fabric. Next the fabric is dipped in a solution of calcium chloride, which corrals the alginate in place so it will not bleed out of the desired area on the cloth. In a culinary application this creates a gel membrane around a liquid center of something edible, e.g., fruit juice.
Indigo-alginate paint, calcium chloride, reducing vat. 
Indigo printed cloth in calcium chloride solution. 
Immersing in the lime/fructose solution which has turned a gold color.
Lastly the textile goes into a lime/fructose reducing vat, which is the 2-3 part of the 1-2-3 vat (this one has no indigo in it). After a few minutes of immersion, the cloth with the reduced indigo print is brought out into the air to oxidize.
Katazome stencils on persimmon paper from last summer. 
Katazome stenciled rice paste resist. 
Katazome stencil with rice paste resist. 
A freehand turtle design made with rice paste resist, painted over with indigo-alginate mix.
Et voilà! A dark blue print stays in place on the cloth.
Now for the trial and error portion of the lesson. In my experiments quite a bit of excess indigo washed out after painting/printing, leaving a light gray-blue print or mark. Not the beautiful blue hue I had hoped for. I will need to try different solution concentrations, amount of time in the various dips, and perhaps different temperatures. So many variables to experiment with!
I Dyed it My Way 