When brick pavers loose their original beauty and dirt becomes embedded within the surface, it is necessary to acid wash the pavers. You need to select the appropriate materials, know how to mix them in the right proportions and how to use them in a safe and efficient manner. The acid wash will restore your pavers to their original form of beauty when they were first constructed.
Select the appropriate amount of muriatic acid. Usually 1 gallon of muriatic acid to 5 gallons of water will clean 200 sq. ft. However, if the pavers are a little more dirty than normal, then you may want to increase the potency of the acid. Maybe 1 gallon of acid to 3 gallons of water.
Purchase a good acid brush and brush handle. You will usually find the brush and brush handle at the same store that you found the acid. Make sure the brush is a good stiff brush with short bristles. If the pavers that you are cleaning have a deep, pitted surface, then you may want to go with a longer bristled brush. Again, surfaces vary and it will be up to you to determine the bristle length.
Use one 5-gallon bucket for mixture. You may have one around the house or you may purchase one from the local hardware store as well.
Make sure all extra dirt and debris are swept off the pavers. Wet the pavers with a garden hose. Add about 3 gallons of water to the bucket at first, and then the entire gallon of acid. Dip the brush in and scrub a small surface on the pavers. If the mixture has a yellow tint to it, then you may add more water. You want a white foaming action when the acid is applied to the pavers. Scrub a larger area, about 20 sq. ft., making sure that the area remains wet before applying acid. Allow the acid to set for 10 to 15 minutes. While the mixture cleans, scrub any hard, set in areas with the wire brush. Wash the acid mixture off, and repeat until you have cleaned the entire area.
Once the entire area has been cleaned and you are satisfied with the outcome, respray the pavers with the garden hose so as to ensure that no acid remains on the pavers.
The fumes from the acid are dangerous. Never inhale the fumes. Always wear protective clothing. Keep hands out of the acid mixture.