The easiest commercial pressure washing chemical which can be used is citric acid. It's really not necessary to buy this acid from the market. This can be achieved by using any citrus fruit but most likely lemon juice can do the wonders. Oxalic acid can be used to remove the rust and sodium hypochlorite can be used to remove stains and dirt. Pressure washer degreaser should be of an industrial strength so that it can penetrate deep to give you the best result. Pressure washing chemicals are also made up of alkaline base to remove the rust which can even penetrate the concrete. These all should be of industrial strength quality as the cleaning will not be possible without the strong agent and the poor functioning chances of the washing equipment is very high. To avoid such mishappening the customer is advised to buy the product only from a reputed store.