FEEDBACK FRIDAY: Mordanting Fabric Before or After Indigo Dyeing

This week on FEEDBACK FRIDAY: When overdyeing indigo with weld, mordanting before or after?

Every week for FEEDBACK FRIDAY, we are emailed with questions from our natural dye community asking simple and complex questions that we thought might be worth sharing. Of course, all of your burning questions are answered by natural dyer in chief, Kathy Hattori, Founder of Botanical Colors. This week’s look at mordanting before or after indigo dyeing is a common question.

I would like to know if I am over dyeing indigo with weld do I need to use a mordant on the fabric for the weld? And if I do need to use a mordant, do I use the mordant after indigo fabric or before I indigo the fabric?

This is the overdye procedure.
1.  Scour fabric, noting the dry weight of fabric.
2. Dip in indigo until it’s the shade that you want, then neutralize, and rinse until the fabric is clean.
3. Mordant fabric.
4. Dye fabric in weld (or pomegranate, fustic, cochineal, madder, etc.) and finish as usual

Overdyeing the opposite way (dyeing the piece in natural dyes first) and then overdyeing works as well, but there’s always the risk that the pH of the indigo vat will alter or strip the shade with pH sensitive dyes, and dye runoff will alter the appearance of the indigo vat, which can be confusing for newbies.

Love indigo but are a little nervous to just dive in? Check out the many questions we’ve been asked.