What factor would likely determine whether a product is applied using the bowl-and-brush method or the applicator bottle method?

The viscosity of a product is a critical factor that influences the method of application used in coloring hair. Products that have a high viscosity, meaning they are thicker or more gel-like, are more effectively applied using the bowl-and-brush method. This method allows for greater control and precision, which is essential when working with thicker products that need to be evenly distributed throughout the hair.

On the other hand, low-viscosity products, which are more fluid or runny, are typically applied using an applicator bottle. This method is efficient for spreading the product quickly and evenly, especially when it comes to covering larger sections of hair or when speed is a priority.

By considering viscosity, a stylist can choose the most suitable application method to ensure the best results for the client's hair color service.