Methods for forming a nanotube fabric with a controlled surface roughness (or smoothness) and a selected degree of rafting are disclosed by adjusting the concentration levels of a selected ionic species within a nanotube formulation used to form the nanotube fabric. In one aspect, the present disclosure provides a nanotube formulation roughness curve (and methods for generating such a curve) that can be used to select a utilizable range of ionic species concentration levels that will provide a nanotube fabric with a desired surface roughness (or smoothness) and degree of rafting. In some aspects of the present disclosure, such a nanotube formulation roughness curve can be used adjust nanotube formulation prior to a nanotube formulation deposition process to provide nanotube fabrics that are relatively smooth with a low degree of rafting.