Home » Tip of The Day » Decrease or Increase The Hardness of The Brush ToolDecrease or Increase The Hardness of The Brush Tool June 3, 2016. Posted in: Tip Of The Day. You can decrease or increase the hardness of the brush tool by pressing Shift and { or } (left or right bracket) keys. « Previous Photoshop Tip: | Next Photoshop Tip: » Sign-up for the PTC Newsletter so that you'll never miss a tutorial!. Your Email Address: