During which stage of the eyelash growth cycle are 12 to 14 mm eyelash extensions recommended for application?

In the context of eyelash extension applications, the correct stage for the recommendation of 12 to 14 mm extensions is the telogen stage. During this phase, the natural eyelashes are in a resting period where they are not actively growing, which allows for safe and effective application of longer extensions.

Applying longer extensions during the telogen stage is advantageous because the natural lashes are more stable and less likely to experience stress or damage from the added weight of the extensions. The natural lashes are also less likely to fall out during this time, making it an optimal moment for the application of extensions that enhance length without compromising the health of the natural lashes.

In contrast, the anagen stage is characterized by active growth, and extensions might interfere with the natural growth process. The catagen stage is a transitional phase where the lashes begin to detach from the hair follicle, meaning stability for extensions is not guaranteed. The maturation stage isn't generally recognized in the context of the eyelash growth cycle as it pertains to extension applications.

This understanding of the eyelash growth cycle is crucial for determining the right timing for extension application to promote both aesthetic goals and the health of the client’s natural lashes.