Okay, gang, it's time to continue with the thrills of selecting the right clear water-repellent for your job. Now settle down, I know that you're excited, but you'll just have to keep calm. That's right, easy, easy... breathe in, breathe out, breathe in, breathe out, breathe in...
Once again, we have something being promoted and shown to the public as "Here is a product that will do everything that you ever needed, below grade and above grade, and you don't have to do a thing but spray it on with a little garden sprayer." Well, the only correct thing here is that you can put it on with a garden sprayer. But let's make something clear; this is traditionally a water-repellent. This means that it will repel water, for short periods of time! And if you have any large amount of water pressure, then it won't withstand it. So where do you put it? Anytime that you don't want the masonry surface to change, is where you put this type of product down. For example, you want your brick to still look like brick, then you put down a water-repellent. But again, be very careful with the product that you buy. Whatever product that you use, you have to remain with that product line because chemically, Brand X will not bond to Brand Z, and if you do try to put two different brands on top of each other, then you might end up with peeling and discoloration. So what and how do you buy a product?
There are three finishes that you can get with a water-repellent: High gloss, which looks like the surface has just been rained upon; medium gloss, which looks like it had rained a little while ago--there is no sheen, just a deeper color; clear or satin, which gives a slight deepening of the color, but for all intents and purposes, is clear. Now, the gloss type of coatings will leave a film across the surface, so don't put down a gloss product where you are going to walk and it is already slick. With this product on, you could look like butter on a hot skillet trying to keep your balance. Average touch-up time with this product is about every three to four years. Reapply is five to seven years. This should apply to all liquid applied coatings.
There are many brands and chemical types of water-repellents. You are buying three things. First, the main active chemical, or solids, be it acrylic or silicone (acrylics give a shine, silicone gives none, or little surface change). You might also have a can that talks about silanes, siloxanes, and "whatapaintoundestandthisthing." Just relax, they are all silicone-based products. You should spend more for the amount or percentage of chemical, not for the name. Example, a semi-gloss may have 7% solids where a high gloss will have 15 to 20% solids. Too much solid content, and it won't go into the surface of the masonry or concrete--it will just lay there, so be careful in your selection.
The next thing that you are paying for is the carrying agent. This is the product that is actually putting your repellent into the surface substrate. So what do you need to know here? Is it resistant to calcium (will cement hurt it?), and will it harm your plants, wood, glass, etc. If it does, then be careful when you apply it. Also make certain that the product is new. With winter coming on, the temperature has dropped, and this will at times affect the quality of the chemicals. Make certain that your product has not gone through any freeze-thaw cycles.
The last thing you are buying is the filler. This is what is left after the carrying agents and solids. Again, make certain that the filler is compatible to your surface during application.
Where do you use this product? Above grade only. Never, never, never, ever put this type of product below the dirt line. It won't work and it won't last. And you can't put the right product on top of it, because it won't bond. In other words, you're in trouble and I can't help you out too much. There are things you might be able to do, but your options are limited, so the best thing is just don't do it! .
Next week I'll spend time answering any questions you might have, or ones regarding this topic that have been commonly asked before. So write or call if you have any. Until then, see ya'.
Originally published in the Daily Courier December 9, 1999