Final answer:
For resistant hair, Shades EQ processing time may be extended up to 40 minutes, and applying gentle heat can help improve color penetration. Always perform a strand test before full application.
Step-by-step explanation:
When using Shades EQ for resistant hair, it's important to ensure proper penetration of the hair cuticle to achieve the desired coloring effect. First, consider extending the processing time; typically, Shades EQ should be left on the hair for about 20 minutes at room temperature. However, for resistant hair, you may need to leave it on for up to 40 minutes. Additionally, applying gentle heat during processing can help improve color penetration into resistant strands. Remember, it is vital to perform a strand test before applying any color formulation to the entire head to check for the desired result and prevent any unexpected hair damage.