Avoiding Fading

Q: I dyed several pieces in a ferrous vat and had great results. They came out with great deep blues. However, they have faded terribly since then. Any idea what I might be doing wrong?

A: The typical culprits on fading are:

Choice of material being dyed. Some materials have received inadequate preparation and have some sort of coating remaining on the fiber itself which keeps the indigo from dyeing directly to the cellulose. Well scoured materials will dye more evenly and will hold up to all kinds of wear (UV, Washing). Some fibers also just dye more easily. For example rayon is super easy to dye and linen is more challenging.

Conditions in the vat may have been under-reduced, meaning that the indigo was not in proper shape to adhere to the fabric.

Sediment layering. If your fabric hits the sediment on an early dip, future dips will adhere to the gunk layer you picked up from the sediment and then wash out later as the sediment itself eventually breaks down and moves along.