this is a product review for the ever build 401 high strength brick and patio cleaner one of the best brick and patio cleaners on the market you will see a little close-up of me applying it to some brickwork in just a second and in front of me you can see that I've applied it to a patio slabs wet the surface first apply the acid as per the instructions leave it for 20 minutes scrub it in and then wash it off with a power wash or some cold water on a hose high-pressure is better and then in a second you will see the results of the acid working its magic on the slabs and on the brickwork a dangerous solution it does contain acid so please make sure you've got glasses on a mask and some gloves