A soft wash incorporates special low-pressure nozzles on the end of a pressure washing gun or wand. That is combined with a biodegradable chemical that removes the biological elements (mold, algae, pollen, dirt, moss) and other stains without damaging surfaces on your home or killing your plants. The only time for full pressure (4000psi) should be used is to pressure wash concrete with a surface cleaner that defuses pressure through two nozzles. We apply chemical cleaners under low pressure so that the solution can adhere better to the surface being cleaned. This will allow the formula to react faster and remove the dirt immediately.