When lawns feel spongy or bouncy this is because they have too much thatch in them.  Thatch is bad for a lawn if it becomes too excessive as it acts like a spongy layer on the ground.  This layer slows down the rate at which water and nutrients can get into the ground as well as preventing sunlight from getting to the bottom layers of the grass.  This weakens the grass.

Our machines remove a lot of the thatch leaving the lawns looking a little rough if they've not been scarified before (a lawn that is scarified regular (once or twice a year) recovers quicker and looks more pleasing when done), and within 4-6 weeks of growing weather (sunlight and rain) starts to look good again.

Scarification is one of the main secrets to a healthy lush lawn.