The soy-sized and dyed goods must cure for a “time.” Curing oxidizes the soy, making the bond between the fibers and the soy permanent. According to John Marshall, there are many variables depending upon climate and weather. The work can cure for several days up to several months. I cured my dyed goods for a 3-plus days, hanging above a radiator, before rinsing out the rice paste. The issue with the soy in the dyes is that you don’t want it to sour. So warm, dry air is best for curing. If you cure goods for the minimum then rinse paste out, the soy won’t wash out — you just need to be gentle handling the fabric. The soy continues to cure after rinsing the rice paste out.
I soaked my work in the bathtub for a while to soften it, then rinsed the rice paste off, then gently squeezed it out and rolled it up in a towel to blot, then hung it to dry over the radiator again. There was not a drop of pigment in my rinse water! This thrills me after many years of working with fiber-reactive dyes and frustrated by the amount of water necessary to rinse out the spent dyes.
The final image, below, shows the outcome of the rice paste resist problem documented in my previous post.