The Dry-Treat sealer attaches itself to the building material molecular lattice where it is able to repel liquids such as water. Dry-Treat's special liquid-repelling sealing molecules are thousands of times smaller than the molecules in standard silicone resin or fluoro-polymer type impregnators, and they won't block the pores, so surfaces treated with Dry-Treat's impregnators retain maximum breathe-ablility after treatment. In short - water (and/or oil) are repelled, but water vapor is able to pass out. The reason for this phenomenon is related to hydrogen bonding i.e. the water molecules stick together as a liquid and are subsequently resisted by the sealer. Water vapor does not stick together and travels alone and is able to by-pass the treatment. This means that trapped moisture in the material can evaporate over time and dry out the substrata.