Final answer:
When using the slicing technique in haircutting, the shears should never be completely closed, as this can create blunt lines. Instead, shears should be partially opened to slide through the hair and remove bulk, creating a softer look.
Step-by-step explanation:
When using the slicing technique to remove weight and add movement through the lengths of the hair, the shears should never be completely closed. The slicing technique involves partially opening shears and then sliding them through the hair to remove bulk and create softness or layering. Keeping the shears partially open while sliding them ensures a smoother transition and prevents cutting a blunt line, which can occur if the shears are fully closed.
In essence, the motion should allow the blades to lightly 'comb' through the hair, making clean, thin cuts without creating too much definition. It's a technique that requires practice to perfect, ensuring flexibility and movement in the hairstyle without compromising too much of the hair's length or creating unwanted short layers.