Primary S-carrying species from the molecule as a function of time and different volume densities (from 10⁴ cm⁻³, top, to 10⁶ cm⁻³, bottom) during Stage 3. The vertical width of each component represents how much sulfur is accounted for. We have also used partially opaque boxes to highlight the timescale that is defined by the free fall time of a homogeneous cloud to collapse under ideal gravitational conditions (, i.e., ignoring magnetic fields, angular momentum, and other resistive effects), for reference to other models. The gas number densities, m, and approximate free fall time limits, t_ff, are noted for each plot.