For instance, the delay �me under the condi�ons depicted in Fig. is 0.8 min. Supplementary Informa�on Fig. shows that the 𝑡𝑡 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 decreases as a func�on of flow, especially at higher flow rates (kf > 7.8 µL min -1 ). This observa�on suggests that there is a regime wherein the reac�ve layer can compete with the base but that beyond a specific flow rate, the role of the reac�ve layer diminishes. This behavior at pH 10 was also observed in our simula�ons. The simula�ons showed that the delay could significantly increase at lower pH values (blue lines). This trend, however, could not be observed in our experiments (red symbols). Instead, we observed that 𝑡𝑡 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 did not change significantly as a func�on of pH.