What is the purpose of stemming in blasting operations?

Stemming is a crucial part of blasting operations because it serves to confine the explosive gases generated by the blast within the borehole. When explosives are detonated, they produce high-pressure gases that expand rapidly. Proper stemming ensures that these gases do not escape prematurely from the borehole, which can lead to reduced efficiency of the blast and may cause flying debris or noise pollution.

By filling the borehole with stemming material—typically inert material like gravel or crushed rock—blasters can improve the overall effectiveness of the explosive charge. This confinement generates a higher pressure and a more controlled release of energy, resulting in better rock fragmentation while minimizing the risk of misfires and ensuring safety in the blasting area.

Other options do not accurately reflect the primary role of stemming. Igniting the charge and enhancing visibility are related to other operational steps, and facilitating access to boreholes is not relevant to the function of stemming in the blasting process. Thus, the purpose of stemming is clearly established as a means of confining explosive gases to optimize the blast's effectiveness and enhance safety.