What is the function of the coalescing agent in Multi Jet Fusion (MJF) printing?

In Multi Jet Fusion (MJF) printing, the coalescing agent, also known as a detailing agent, serves to prevent premature fusing or sintering of powder particles in areas where the part is *notintended to be formed. MJF printing involves selectively applying a fusing agent to the powder bed, followed by a heat source that sinters the treated areas. The coalescing agent is jetted onto the powder surrounding the areas designated for printing. It increases the powder's infrared absorption, causing it to heat up more rapidly than the powder treated with the fusing agent. This controlled over-heating causes the grain boundaries of the unfused powder to partially sinter which inhibits any liquid fusing agent from wicked into this space. In this way the edge sharpness and resolution is significantly improved. Without the coalescing agent, the powder around the intended part area could fuse together due to thermal bleed, resulting in a less defined part edge.