Brick, concrete block, stucco and mortar can absorb massive quantities of water. In fact, bricklayers often cover brick and block piles on the jobsite to protect them from rain. The reason is simple. Brick and block have a property referred to as 'suction'. This suction draws water from wet mortar into a brick or a block when it is laid. This, in turn, rapidly stiffens the wet mortar. This stiffening allows the bricklayer to continue to lay row after row of block and brick. If bricks absorb too much water, they can't suck water from the mortar. When this happens, the brick or block 'swims' in the wall.
Penetrating clear coatings are, in almost all instances, the top performer. These products are excellent water repellents. They have a great ability to penetrate deeply, sometimes up to 3/8 inch into a brick or masonry surface.
Penetrants do not form a film on the surface of brick or masonry. Rarely do they change the appearance or color of the surface. They are able to penetrate because of their tiny molecular structure. These products coat the insides of the tiny passageways of the brick and mortar.
The primary ingredients of penetrants are silanes, siloxanes, or a blend of these ingredients. Note that these two ingredients look very similar to silicone. Do not confuse them!
Silanes have a very small molecular structure. They can penetrate deeply into masonry surfaces. Siloxanes have a slightly larger molecular size, but they also penetrate quite well. The interesting thing is that both of these compounds can chemically bond to the silica and alumina minerals often contained in brick, block, stucco and mortar. This bonding property and their ability to penetrate make for long service lives. Often these penetrating compounds can last in excess of ten years!
Samples of a surfaces treated with a penetrative water repellent.
Noble Corporation is a proud stockist and reseller of the Momentive brand of masonry water repellents.
Momentive Performance Materials (India) Pvt. Ltd