Final answer:
A steam machine is used during facial treatments to soften pores, facilitating the removal of comedones and blockages.
Step-by-step explanation:
During a facial treatment, the piece of equipment that can be used to soften pores to allow for easier removal of comedones and blockages is the steam machine. Steam helps to warm the skin and open up the pores, making it easier to cleanse them thoroughly. On the other hand, a microdermabrasion machine exfoliates the skin's surface, an ultrasonic spatula can be used to exfoliate and extract with vibrations, and a high frequency machine is utilized to stimulate, sanitize and heal the skin. While these other devices are effective for various skin treatments, they do not perform the same function of softening pores like the steam machine does.