This being the proper philosophical sublimation, by means of which the perfect method is carried out. And this is why this Art is compared to Woman’s Work, which consists in cooking and roasting until it is done. – Solomon Trismosin

Plate 21 depicts a scene of many women washing laundry. There is a sense of both harmony, and productivity as they all attend the linen in separate stages. In the front left corner is a boiling black cauldron, a number of blackened jugs sit next to it as the fire roars beneath it. To the right is a woman;  she is washing the material in a shallow basin, one of many in front of her. Further right are two more women, beating the cloth in unison, each holding a paddle in their upraised hand.
Behind them a woman hangs the cloths on a line, as another rinses them in the stream than bisects the picture. Further back we see women stretching the linen out on the grass to dry in the sunshine, while another carries a basket full of clean washing back inside the village.
As we learnt in plate 20, alchemy is sometimes referred to as women’s work and child’s play, and this plate represents the women’s work part of that phraseology. The washing and purifying of the linen we see in the plate is a perfect analogy for the operations we find in alchemy. The heating, washing, rinsing and drying are all operations that are also applied to the prima materia in the search for the philosopher’s stone.
The bleaching and whitening of the linen also represents the movement from the black nigredo stage into the white albedo stage. In the lower right-hand corner of the plate, resting on a washing tub is a black cloth, suggesting that it too will become white after washing. The text aligns the process of sublimation to this plate, the process of distillation. Note the heavy clouds that sit above the women washing;  these too are part of the process. The women boil, wash and rinse the material, and then dry them in the sun, the water is sent back into the clouds, and comes back down again to create the rivers with which the linen is washed.
Albedo, while meaning white, also literally means ablution, which means washing away impurities. Ritual cleansing is used in many religious rites to purify the body. This part of the alchemical process is the longest: the constant washing and repetition, though it is also called the lesser work. This process is readying the material (or body) to regain its purity and receptivity for the soul.

We’ve gone from black to white and we have done the heavy lifting. All that is left is the transformation to Red, the Rubido, and the fulfillment of the Philosopher’s Stone which we will find in the final plate.