Before we discuss how Rodin’s treatment of contour line deteriorated over the course of his drawings, it is first important to acquaint ourselves with his artistic process. Instead of drawing from a single model statically posed, Rodin invited several models into his studio at once, and encouraged them “to relax, stretch, and sprawl, pull up their legs or spread them, because to him these movements were just as natural as, say, a child’s kicking and playing with himself or a cat’s licking itself clean” (Güse 222). As Güse notes, it was this “natural” element Rodin was interested in - particularly concerning the encounters between and among the models, and he was known to sit still for hours, simply watching them, until he felt he had achieved a degree of invisibility sufficient enough to begin drawing. In this way, Rodin produced thousands and thousands of drawings, dashing them off in seconds without lifting his pencil from the paper, moving on to the next sheet almost before he had completed the first (Bonnet 9). But if the drawings were initially all just cursory pencil sketches, how did Rodin produce the striking watercolors and collages that are grouped with his drawings today?
It seems that Rodin was never really finished with his sketches by the time the models left the studio. He developed a habit in his later years of storing away the quick contour sketches, and then taking them out again, days, months, and sometimes even years later to rework them, going over them with watercolor or gouache, adding secondary shadings of color and shadow (Bonnet 18). 
He did this, as Güse suggests, in order to “lend them additional ‘sweetness’ … or better, to lend them charm and a soft glow” (Güse 223). It was often the addition of this “soft glow” that first began to blur the lines between bodies in the drawings. Beyond the addition of watercolor to the pencil drawings, Rodin also took to cutting them up and reassembling shapes together in previously unrelated arrangements. This led him to combine figures of women who had not originally posed together, and in this way create completely new compositions and combinations of figures, stripping them not only of their individuality, but also of the lines that defined them. Indeed, as Bonnet points out, “Many of the lesbian couples were produced on this principle of montage and collage” (Bonnet 19).
Thus, through the use of both paint and scissors, Rodin obscured the lines between his figures and melted the bodies deliberately together. “Scissors respect line no more than does color,” jests Claudie Judrin (Judrin, “Rodin Watercolors” 19). But neither, it seems, manipulate line so well as Rodin. His evolving process assembles itself nicely into a logical chronology: the pencil sketches came first, followed by the reworked watercolors, and ending with the paper cutouts. Thus, as the years went on, Rodin’s lesbians became less and less explicit as specific figures defined by contour line, and therefore became less and less erotic.
right, above: Rodin, Auguste. Two Women in Each Other’s Arms. Undated. Musée Rodin, Paris.
left, below: Rodin, Auguste. Two Female Nudes, Semi-Recumbent. Undated. Musée Rodin, Paris.