The look of an acid stained concrete surface is attractive for many reasons. Its unique finish characteristics are such that the uneven, ugliness of plain concrete becomes the star of the show. Acid stain will not mask, nor cover imperfections in the concrete, but it will use transform them into something quite attractive. Though professional skills may result in a more professional look, the artistic nature of the process allows the handy DIY’er to achieve a most satisfying look just the same. Just follow some necessary principals and behold the results. Keep in mind this is merely an overview and not detailed instructions. For best results, always reach out to a qualified decorative contractor in your area for your job. Let the experts handle it so you can best enjoy the results.
Please refer to the data and instructions from the specific manufacturer/supplier of your material. As with any concrete project, many unpredictable results can result due to unknown or unforeseen circumstances.
To test the absorbency of the particular slab, you need to throw some water down and watch the results. You want steady and even absorption into the surface. Make sure to test the entire slab because you have to be able to remedy inconsistencies. If the water does not absorb steadily and evenly, curing agents or sealers may be blocking the surface, thus they will effect the application of the acid stain and must be removed. For sealer removal, many methods may be employed such as solvents, sanding, and grinding. If you choose grinding, be sure to use a proper disk, such as a grinding cup, to avoid swirl marks which will easily transmit otherwise. In addition, be sure to do a thorough cleaning with a good degreasing cleaner, such as TSP, to remove any grease and oil, paint drops, taping compounds, caulk, or other surface contaminants. If patching is required, know that it will take stain differently than the rest of the floor and will be visible (but better than a hole.) As an option, you may consider sanding the entire floor. It will often accentuate the high spots by opening up the pores even more allowing more stain to penetrate.
Finally, you’ll want to do one last washing to remove the remaining dust and debris. Water, detergent, and then wet vacuum it dry. Any streaks, lines, footprints, etc. can effect the final finish.
Applying the stain:
Manufacturers vary on when to apply stain. Many default to the standard 28 day cure time before staining is to be started. A few say 14 days. Some installers have had success after 3 days.
Keep in mind that the younger the slab, the more intense the color. This means that the older slabs requires a higher strength solution. So, if you’re trying to match stain for new concrete with stain for existing concrete it is going to be extremely difficult to achieve, and we do not advise that you attempt to do so. This also means that product cost can go down significantly when staining new concrete because of the ability to dilute the solution more freely.
The actual application method can also alter the look, so have a plan in mind there. A sprayer is most common and you have to be sure to have an acid approved sprayer. Acid eats metal so no metal parts. Inspect carefully! Tips that produce a circular pattern give the most consistent results and allow for less “marking” of the spray pattern. When spraying, follow up with scrubbing it in with a medium bristle brush to ensure more even penetration. Some choose to let it remain on the surface resulting in a more splotchy appearance. A light follow up spray will remove any brush markings. This can be done with another color to achieve a more mottled look. An other option is to use water. Water can be used before the acid goes down giving you a more diluted look in areas (as long as you are not scrubbing away most of the differential). You can also add water after it is down to create a more “fluid” look to the surface. Some installers have even used solvents such as mineral spirits to alter the drying pattern of the water to achieve some dramatic results. Of course, beauty is in the eye of the beholder and acid staining is a prime example. Stains may be applied by paintbrush but care must be taken to minimize brush marks, and this method is usually reserved for small areas. Rollers are the same except provide even more challenges due to the lines they create. However, there is one installer in particular that used a roller to create a check pattern on a pre-wet floor and which resulted in a one-of-a-kind “liquid checkerboard” which garnered high creative praise.
However you choose to apply your stain, bear in mind that over spray, splashes, spots, etc. can be impossible to remove from unintended places. Carefully mask off anything and everything you do not want ruined before starting. Lastly, do not discount the power of color. Even a very diluted (5%) acid solution can produce a noticeable, yet subtle color effect to plain concrete.
If saw cuts or stencils are in the plan be sure to plan out the desired look. Cuts can take a different look depending on pre- or post- stain. If you want a more even look, cut after because the stain will darken the more exposed concrete near the cuts more intensely. If the lines will serve as a distinction from one color to the next, cut first as it will keep color separated easier than other barrier methods that may bleed such as tape.
When you are finished staining and it has had significant time to take effect and dry, you can neutralize and clean. A good scrubbing with water and baking soda, followed by removing residue with a wet vac is a good regimen. Follow up with several good moppings with clean water until wiping the floor with a white t-shirt comes up clean and you are good to go.
Sealing and preserving your finish is equally important to your prep and staining. Most issues with stained concrete that occur after application revolve around sealer failure or lack of sealer maintenance. High traffic coupled with no maintenance can show wear in no time. Be sure to use a high quality, appropriate sealer or coating to ensure a long and lustrous life to your work of art.
If you have any further questions please feel free to contact us for expert technical support.