Indigo Vat Troubleshooting: Tips on Sediment and Sharpening Your Vat

Q: I mixed up all the ingredients using only a gallon or so of hot tap water and noticed that there was a lot of sludge at the bottom of the container. The indigo and iron seemed to dissolve but the lime made the liquid look ‘milky’ and thick. Should I not pour the sludge into the vat?

A: The sediment is good! It is the active medium for the reduction (activation) of the indigo. It is a necessary part of the ferrous vat. That said, it is good to make sure that this sediment has settled out into your final vat before dyeing - as it can stain fabric when it has first been mixed up as it contains iron. The stains can be removed with citric acid and soap. I only dye a handful of things each day and always stir up the vat after dyeing and allow it to settle out before dyeing again.