Comparison of abundance profiles obtained from RT modelling (solid lines with shaded 1σ uncertainties) and chemical modelling (dashed lines) for SiO and SiS. The circles denote the R_e of the respective RT models and the squares mark the R_e of the chemical models. The arrows denote open error bars, indicating that the abundance profile has not been well constrained. The error bars on the chemical model R_e denote the estimated uncertainty in the chemical models based on reaction rate uncertainties (Van de Sande et al. 2025). The blue dotted lines for AFGL 3068 show chemical model abundance profiles with different initial SiO abundances (1.0e-6, 2.0e-7, 2.5e-9).