Here is what I found so far:
In the late 1680s William Rittenhouse immigrated to America from Holland. A papermaker by trade, his first stop was New York. Since there were no printers there, and thus no demand for his product, he moved to Philadelphia. He settled in Germantown, which was located outside of Philadelphia and, as its name suggests, was home to many German and Dutch immigrants. Rittenhouse, himself German by birth, had learned the papermaking trade in Amsterdam.
Soon after his arrival in Philadelphia, Rittenhouse went into partnership with a printer named William Bradford and two other men to construct a paper mill along the Wissahickon Creek. Although he owned one-fourth of the new company, Rittenhouse was clearly the most important member of the group; the others relied on his skill to build and operate the mill.
That a paper mill was built near Germantown was no coincidence. It made sense in terms of both the source of the raw materials as well as the location of potential customers for the finished paper. In that period, paper was made from the pulp of linen rags. The cloth scraps were pounded by a water-powered trip hammer in the paper mill. There was a steady supply of scrap linen in Germantown, since the Germans and Dutch of that settlement were known as skilled weavers of linen cloth. Linen is made from the fibers of the flax plant, and large quantities of flax were grown in the surrounding countryside. So from field to loom, and cloth to pulp, Germantown produced the necessary raw materials for the manufacture of paper. (The "brotherhood" of the cloth and paper making trades is related in first poem of Student Handout 1- Poems about Papermaking.)
Likewise Germantown's location just seven miles outside of Philadelphia made it convenient for getting the product to customers. Philadelphia was already a significant colonial city by the turn of the eighteenth century, and so it was a growing market for paper. One of the mill's most important customers was Bradford, a successful printer and one of the mill's founding members.
By 1696 Bradford had gotten into quarrels with some of his patrons and financial backers, and so he left Philadelphia for New York. He leased his interest in the paper mill to Rittenhouse and his son Klaus for ten years in exchange for a set number of reams of printing and writing paper annually. (Bradford's interest in the mill, along with his departure to New York, is referenced in the second poem of Student Handout 1- Poems about Papermaking.) Bradford's departure from Philadelphia served to expand the paper mill's market to New York as well. In fact, until around 1710 all the American paper used in Philadelphia and New York came from the Rittenhouse mill. By this time a second paper mill was constructed near the first by William DeWeese, a relative of the Rittenhouse family.
By 1704 Bradford had abandoned his claims, and by 1706 Rittenhouse had bought out the interests of the other two partners, thus making him sole owner of the prosperous mill. His family stayed in the papermaking business for the next four generations.