Relative abundances in each grain size bin as functions of density in the L1544 model at t = 10⁴ yr (top) and at t = 10⁵ yr (bottom). The red lines correspond to model M3, while the blue lines correspond to model M4. The green lines show the relative abundance of the grains in each bin, shown only in the bottom left panel for clarity (but note that the y-axis scaling is different in each subplot). The effective grain radius increases with bin label.