dezibeereal asked: what is a fan brush used for

A fan brush can be used for a few things! :)

• Applying a light dusting of powder to set your makeup. A fan brush picks up very little product so it’s great if you want to set your makeup with a powder because it prevents applying too much looking powdery or cakey.
• Applying a light layer of blush in a small area. Sometimes powder brushes or blush brushes are rather big so it’s easy to apply too much blush. A fan brush gives you a little more control over how much blush you’re applying.
• To highlight the face. Since fan brushes are so thin and narrow you can use it to highlight the cheek bones, down the nose, the temples and the upper lip. It’s not only the right size and shape to highlight but since fan brushes pick up less product than a normal powder brush you can apply a less dramatic highlight and build it up as desired. This prevents you from looking like a disco ball if you just want a subtle highlight. 
• To contour/bronze the face. Some fan brushes are rather thick and full making it great to lightly contour the cheek bones. Fan brushes can give that light, thin even chiseled contour unlike some big powder brushes. You can even use a fan brush to apply a light layer of bronzer around the edges of the face like the temples to get a light bronzed look never looking too overdone.