Time evolution for the species closely related to the formation of CH₃OH and hydrides in the ice predicted by some of our KMC models (extremes) for the collapse phase. We note that the heavy fluctuations observed for CH₄ is a finite-size effect, due to the very low concentration numbers generated by the KMC on the grain (CH₄ abundance is found to fluctuate between 1 and 0 on our 50 × 50 lattice). For the high-density slow-collapse model (model 9) towards NIR38 (T = 14 K, A_V = 60 mag), the results are shown for 95.9% of the intended collapse time.