Final answer:
To test the microdermabrasion level, the under the jawline is the preferred area of the skin because it is less visible and has a similar sensitivity to the face. This allows for a safe test patch that won't be overly evident if irritation occurs.
Step-by-step explanation:
When testing the microdermabrasion level, it's important to choose an area of the skin that is generally representative of the face but also discreet enough for a test patch. The recommended part of the body to test the microdermabrasion level is under the jawline. This area allows you to observe how your skin might react to the treatment without it being overly visible to others in case of unexpected redness or irritation. As the skin on the face is often more sensitive than other body parts, testing in a less conspicuous area like under the jawline is a prudent precaution before proceeding with treatment on more visible areas.
Testing microdermabrasion on the inside of the wrist or outside of the ankle isn't recommended due to the skin texture and type differences compared to facial skin. The side of the cheek, though representative, is usually too visible for an initial test. Hence, for safety and aesthetics, the under the jawline is the most suitable area for testing. After the test, watch the sampled area for any adverse reactions before deciding on a full-scale treatment.
For testing microdermabrasion levels, the under the jawline is the recommended area due to its discreteness and similarity to facial skin. Observing reactions here is a good indicator for how the rest of the facial skin might respond to the treatment.