We will always assess whether a job needs chemical treatment before just applying it. A pass over the entire surface will firstly be done to remove surface dirt, grime and algae. Then we will visually assess the results as to whether chemicals are needed. For the majority of our jobs we will use a form of chemical treatment as more often than not we find either stains such as rust or oil stains hidden under the top layer of grime or in most cases the black spot (black lichen) simply has not budged from the high-pressured water alone. All our chemicals are licensed, HSE approved and label compliant and we store, transport, handle, dilute and apply these chemicals in the safest possible ways to ensure not only our staff are kept safe but the public are safe along with their properties and the local wildlife and watercourses.