1. It’s supposed to rub off. That’s why blue jeans fade.
2. Certain cultures attribute indigo crocking to its authenticity and prize the way that excess indigo comes off on the hands or body. I found a description from Duncan Clarke of Adire African Textiles on how West African cultures dye and prepare indigo cloth:
“After the dyed cloth had dried it was customary to beat the fabric repeatedly with wooden beaters, which both pressed the fabric and imparted a shiny glaze. In some areas additional indigo paste was beaten into the cloth at this stage, subsequently rubbing off on the skin of the wearer in a much desired effect.”
3. Okay, we are not that culture. If you dip in a well-prepared vat with clean fibers and oxidize in a hydrogen peroxide bath afterwards, you should be able to minimize crocking.
Minimizing Indigo Crocking on Yarns and Fibers
Some observations
* Indigo on cellulose and bast fibers such as cotton, linen and hemp appear to crock less
* Indigo dyed fibers that will later be spun seem to crock more.
* Indigo dyed on dirty or greasy fiber will not bond well and will rub off.
* Something that is dipped incorrectly in the first place will crock (or show other signs of stress like streaking, premature fading or yellowing).
* Some indigo powders are filtered more than others resulting in a purer vat and better adhesion of the indigo to the fibers.
* We’re calling the creation of the stock or the paste the indigo “mother” (a term that I learned from Denise Lambert of Bleu de Lectoure).
Considerations
-Indigo needs a bit of time to adhere to the fibers. A two or three second dip will often result in streaky indigo that crocks. It’s better to create a very lighter vat and let your fiber stay in it for a longer period of time than it is to dip quickly in a very dark vat.
-If there’s a lot of sediment at the bottom of your vat, keep the goods away from this deposit.
-A very old and overused vat can be bad news. It’s filled with sludge, dye runoff and probably a bit too much reducing agent and is quite temperamental and can go off balance very quickly. It’s better to start with a fresh vat if you are working on a tricky color.A correctly balanced vat is the first line of defense against crocking. Indigo needs an alkaline and reduced environment in order to bond securely with the fiber. Too low of a pH and the indigo doesn’t completely dissolve. Too little reducing agent and the indigo will rub off. Are you feeling like Goldilocks checking out the indigo vats? It’s important to review your indigo technique an
Before dipping
Soak your clean, scoured textiles in lukewarm to hot water for at least 20 minutes. Take care with wool fibers to avoid felting.
Your vat will be ready to use as soon as it’s cool enough for you to comfortably dip in it and the indigo liquid is clear. However, you can also save your vat for later use. The strength of the vat will deepen after it sits for a couple of days, as the indigo benefits from curing.
How to dip
Indigo dyeing works by building up color with multiple dips in a vat, allowing the textile to oxidize and rest in between each dip. When you dip a textile in the vat and remove it, the textile will first have a greenish color, then turn to blue as it interacts with oxygen in the air and the indigo bonds to the fibers. This process is called oxidation.
If you have a layer of foam or cluster of bubbles on the top of your vat (called a flower), carefully remove it, setting it aside to return to the vat at the end of dipping. Take your textile out of the water it’s soaking in and slowly and carefully lower it into your vat.
Once the textile is fully submerged, use your hands to gently open any folds or creases and ensure that the entirety of the piece is exposed to the vat liquid. If you’re dyeing an article of clothing, open up the arms or legs, make sure that pockets or flaps of fabric are fully opened, and check the hems to ensure that they aren’t folded over on themselves. Do not let the fabric or yarn float to the surface and also keep the textile from touching the sediment layer at the bottom of the vat.
Keep the piece submerged in the vat for one minute, gently moving the textile through the liquid, then slowly remove it from the vat. Carefully wring it out over the vat to keep as much indigo in the vat as possible. The piece will be greenish-yellow when you remove it from the vat and slowly turn blue once it’s in the open air. Open the textile and shake out any folds. Hang the textile or fiber and allow it to fully turn blue. Once there is no more green or yellow left on the piece, you can repeat the dipping process as many times as needed to build up darker shades of blue. Be sure to dip your piece in the vat at least twice to stabilize and even out the indigo color, even if you are trying to create light blue shades. Keep in mind that once you rinse and dry the textiles, it will be one or two shades lighter than it appears at this stage, so dip one shade beyond what you want the final color to be.
Step 2 – Oxidizing
I oxidize in a water bath that contains hydrogen peroxide and a small amount of soda ash. If I am dipping protein fibers, I often omit the soda ash. The hydrogen peroxide speeds up oxidation and seems to “clean” the dyed fibers so there is subsequently very little wash out and I’ve found that I have very little crocking.-Use 1 pint of 3% hydrogen peroxide(the kind that comes from the pharmacy) per pound of fiber being dipped. Mix in a 5 gallon bucket of cool water. Dissolve 1% soda ash on weight of the fiber and add to the bucket of water.You can use this mixture for the day’s indigo dips.
-Immerse your yarn or fiber or cloth in this mixture after removing the goods from the indigo vat for 15 minutes. You can let the excess indigo drip into another catch basin first if you wish.
-Remove the goods from the hydrogen peroxide bath and allow the goods to continue to oxidize for 30 more minutes.
-Repeat the dips until your fibers are the desired color.
Step 3 – Neutralizing
-Neutralize the dyed fibers in a second bath that contains 5% acetic acid on the wof and let soak for 30-45 minutes. Use about 1-2 Tablespoons (30ml) of vinegar in a 5-gallon bucket and let it soak for 20 minutes.
-Remove and rinse in cool water. The rinse water should run clear after two or three rinses.
-Let the fibers dry out of the sun.