Certain spin-coatable liquids and application techniques are described, which can be used to form nanotube films or fabrics of controlled properties. A spin-coatable liquid for formation of a nanotube film includes a liquid medium containing a controlled concentration of purified nanotubes, wherein the controlled concentration is sufficient to form a nanotube fabric or film of preselected density and uniformity, and wherein the spin-coatable liquid comprises less than 1×1018 atoms/cm3 of metal impurities. The spin-coatable liquid is substantially free of particle impurities having a diameter of greater than about 500 nm.