Used for a plastered wall (very porous), in the following proportions, close to what is recommended: - 300 ml of the product diluted in 5.5 liters of water with 20 to 25 m² of surface treated. I used a sprayer 5l usually dedicated to weeding. The mixture was very fluid and does not pose a problem. I sprayed until the quantity is such that it begins to flow along the wall, taking care that excess flows over areas already humified. Difficult to assess the results because the wall is not smooth but it seems that the product is highly effective: a portion of the spray have been driven by the wind and spread over a tiled terrace, we can clearly see the effect water pearl that instead of spreading as before, while the amount of product on the terrace had to be really low. I was amazed at the huge prescribed dilution ratio, 20 liters of water for 1 liter of product, but the product keeps its promises and my slight overdose because of the porosity of the wall was perhaps not necessary.