Mistake eraser: By design, a fan brush fans away product. So if your powdered makeup products (especially eye shadow) are leaving flecks behind, a light swipe of the fan brush can easily wipe away the excess.
Blusher/bronzer: If you want just a sheer touch of blush or bronzer on your cheeks — or you tend to have a heavy hand when it comes to makeup — a fan brush will enable you to create a softer look. In turn, use the brush's flat shape to assist in contouring where needed.
Powder foundation: Get a more precise powder foundation application when using a fan brush.
Diffuser of color: Break out that fan brush to blend out harsh lines or to create new shades with your powder cosmetics. Tip: use it with darker shades to tone them down or with a highlighter to provide a luminous effect.
Skin care applier: Make a mask or peel go on all the more smoothly with a fan brush. Better yet, you'll get nice coverage without using a lot of product.