A common problem with the appearance of bricks is efflorescence, a white or greenish coating on brick structures. This not only spoils the appearance, but also accelerates the destruction of the masonry, causes defects in the form of chips, shoots, a decrease in frost resistance and deterioration of the brick grade in strength. Efflorescence is formed by the evaporation of capillary moisture, which can be found both in the product itself and in the masonry mortar, and the subsequent crystallization of salts on the surface of the brick. To prevent efflorescence, it is proposed to treat the product after firing in a tunnel kiln with a 40-45% aqueous solution of potassium methylsiliconate (organosilicon water-repellent liquid). The concentration of potassium methylsiliconate solution was experimentally selected. The optimal ratio of an aqueous solution of potassium methylsiliconate to water was 2:1000. An analysis of the appearance of the front surfaces after treatment with the analyzed solutions on the 1st, 3rd and 7th day after treatment is presented. The appearance of the product after treatment remains unchanged, vapor permeability is preserved, and gas impermeability of the material does not change. Water absorption of the products was determined at atmospheric pressure in water with a temperature of (20±5 ℃). Treatment of products with an aqueous solution of potassium methylsiliconate leads to a slight increase in water absorption rates, which will preserve the quality and strength of the brick in areas with severe climatic conditions. Frost resistance tests were carried out with volumetric freezing. A positive effect of treatment with a water-repellent solution on the frost resistance of the brick was established. The results of strength and bending tests confirmed the effectiveness of using a potassium methylsiliconate solution. The test samples were assigned strength grade M 250.

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