Today I am going to write about the most common and cost effective Decorative Concrete re-surface(overlay) application and that is the Spray Texture. Typically used in conjunction with a stencil that reproduces a tile or stone pattern. (Note: I am explaining the basic and common practices each project is different and should be evaluated before proceeding. Contact your distributor or manufacturer for more information)
a) Explanation of the application process.
b) Explanation of options
c) Comparison to other re-surface(Overlay)
Application Process:
Preparation:
1. Before we begin any overlay/re-surface project the existing substrate is examined for cracks, spalling, stains, and low spots that may produce ponding as well as any other defects. These must all be prepared and allowed to cure/set up before the overlay material is applied. This step is essential so that these areas do not show through the overlay, as the overlay material we are applying is 1/8″ to ¼” thick(thin).
2. Cleaning the existing substrate (concrete). Even if the concrete is brand new I advise not to skip this process as it will make for a complete bond. First use some type of degreaser and your power washer make sure all oil and contaminants and latent particles are completely removed as well as any paint. That means if you need to scrape and use a wire brush that’s what you have to do. As a concrete surface cleaner I like to use Sure Crete’s Super Concrete Renovator (SCR)a mildly acidic detergent at a 3:1 ratio and and use a broom to scrub it around. Rinse off with water and then a quick powerwash.
3. Profile/Etch- This can be accomplished with SCR or Muriatic Acid (4:1 Ratio) apply acid scrub with nylon broom until foaming bubbling stops(do not let dry) and rinse. Interior slabs should be wet-vac and rinsed several times. Power wash with minimum 3000PSI strength powerwasher. Equipping your power washer with a turbo tip will thoroughly etch the surface, exposing the aggregate to ensure a good bond. Note: if using muriatic acid rinse with ammonia (4 oz. To 1 gallon) to neutralize the acid. Rinse the area and let dry.
4. Applying the skim coat: First follow the manufacturer’s directions! Then be aware of the climate conditions. A very hot day may require a little extra water and spraying water on the edges as you squeegee out your skim/base coat. I prefer to use the Marshalltown Adjustable SqueeGee Trowel. Rather than the Bon Tools metal spreader. That is my preference, I am sure if you give it a try you find it will become your preference too. If you are using colors to give grout lines a contrast then you will have to take into account that factor.
5. Stencil or no stencil? Taped out borders? Again ALWAYS follow the manufacturer’s instructions. If you are using a stencil or taping, make sure your skim coat is completely dry before you put a size 12 imprint in your perfectly smooth skim coat!!! If it’s dry now is the time to lay out your stencil and/or border. Take a few minutes think it over and plan it out. Ask yourself a few questions, such as:
a. What direction do I want the pattern to run?
b. How do I want the pattern to end on edges and walls?
Start to lay out the pattern keep it straight all the way! If you are doing a large area a little off at one end, can mean a lot off at the other end. If you are laying out any type of design with straight lines such as tile or brick make sure those lines run straight from one end to the other.
Maybe you have a windy day while laying the stencil you might have to roll some tape and put it under the stencil to keep it down. Blue tape is no good for this. Not enough stickiness. Use the reinforced brick tape or duct tape. You are going to go crazy trying to get it completely flat. Don’t worry too much about that, Ill tell you why in the next step. Just make sure when you are walking on the stencil you don’t kick it or pull it with you feet and knock it out of alignment. Once you have it all laid out and sure it looks straight it’s time to start spraying!!
6. Spraying the concrete. Follow the manufacturer’s instructions for mixing the cement . You may be using a Just Add Water mix(JAW) or you may have to mix your ingredients as per the manufacturer. Here is where you will learn a little something by experience. In Puerto Rico I have found that mixing the cement a little wetter than the manufacturer suggests is the way to go. Sometimes it will stiffen up in the bucket and clog up your hopper. Try to use cold water add ice if necessary as this helps slow down the drying process. If adding colors it’s better to use liquefied colors or to liquefy the powdered colorants so as not to get clumps and uneven coloring. Time to start spraying…..Load up your hopper about half way at first set your sprayer for the desired nozzle spray and hold the spray nozzle perpendicular to the floor. By holding exactly perpendicular you won’t have to worry about those high spots in the stencil. If you come in at an angle you will shoot the cement under the stencil there by covering the grout line and depending on how much you do and where it is located it will look sloppy. Hold the sprayer about 2 feet from the floor or more depending on how much texture you want. The higher you hold the sprayer the more texture you get (in general and depending on your mix). Use circular motion with sprayer to assure good complete coverage. Know in advance if you are going to knock it down, you’ll need to have someone ready with trowel or squeegee. Here in Puerto Rico the stuff dries quick so be ready to knock it down. Basically that’s it. Wait til it dries add a second coat if desired or add a lighter spray with contrasting colors to give depth and realistic attributes. You can add 1 or 2 or even 3 different colors . Lets sa your client picked a terra cotta color scheme. You may use dark gray as your skim coat this will give you a dark gray grout line, use a terra cotta color for your first full spray coat, maybe use charcoal as an accent sprayed very lightly on top of the terra cotta and then maybe a very, very light dusting with white.
Now your done spraying! Make sure each coat is completely dry before starting the next coat!
7. Pulling up the stencil- After the cement is dry it is time to pull up the stencil. I like to give this an HGTV tem I call it the ‘Reveal’. This is where the whole thing comes together. Slowly, slowly pull up the stencil! Start at one end and work slowly to the other end. In general the stencil is not reusable, however I have had to reuse small sections in order to complete an area and save the client from purchasing another roll of stencil. After the stencil is removed take a stiff broom and sweep up all the pieces that are left behind this will alls remove most dust in the grout lines. Go around make sure your grout lines and edges are clean. Now you are ready to apply sealer.
8. Apply the sealer. Follow your manufacturer’s instructions and the design criteria you discussed with your client such as gloss, matte, satin or whatever. Usually here in Puerto Rico in couple of hours it is ready for foot traffic. Wait a minimum 48 hours (or per manufacturers recommendations) for heavier traffic.
9. Clean up and collect your check! Remember these are basic guidelines each project is different. Each product is different. Each installer is different. What works for one installer may not necessarily work for another. Also where you are located in the world has a lot to do with how the product is applied. Even if some manufacturer say it doesn’t, believe me it does. Always refer to your manufacturer’s instructions, consult your distributor and trainer and pay attention to what you are doing. It can be a costly mistake to not plan and pay attention. And always do Good Work!
