To ensure client comfort, it is essential to check which of the following before starting a treatment?

Ensuring client comfort during electrolysis treatments is critical for a positive experience and effective results. Checking the client's pain threshold is vital because individual pain sensitivity can vary greatly from person to person. Understanding where a client stands in terms of discomfort will allow the electrologist to adjust their techniques and possibly apply numbing agents or use specific settings on the machine to suit the client’s needs, ensuring a comfortable experience throughout the treatment.

While other factors such as the electrolysis machine calibration, hair follicle condition, and client's skin tone are important to treatment efficacy and safety, they do not directly impact the immediate perception of comfort in the same way that awareness of a client's pain threshold does. Monitoring and accommodating for pain sensitivity is essential to build trust and enhance the effectiveness of the session based on the client's feedback.