How-To: Staining Concrete Floors
Step 1. – Know Your Concrete Floor: The biggest challenge with staining concrete floors poured in the last 5-7 years is they have almost certainly been machine troweled. Machine troweling creates a more uniformly smooth finish but it sometimes can be too smooth to acid stain. When concrete is too smooth, the acid stain cannot penetrate and will “sit” on the surface to later be wiped away during cleaning. Concrete condition and age are very important for successful acid staining. Keep these questions in mind when determining whether or not your slab is a good candidate for acid staining:
The concrete must be free of debris, dirt and oils, paint, dry wall mud, adhesive, or sealers. Acid stain cannot react properly with the concrete if these conditions are present.
The slab should not have been poured with a waterproofing agent, cleaned with muriatic acid or a heavy tri-sodium phosphate (TSP) solution. The acid stain reaction cannot occur on surfaces treated with these products.
For older, excessively power-washed or mechanically-profiled concrete, the surface must be completely intact with no exposed aggregate or sand particles. Concrete acid stain does not stain rocks, sand or aggregate. Exposed aggregate or otherwise depleted concrete may cause the acid stain to take irregularly, react weakly or produce a color inconsistent with the acid stain color chart.
For slick machine-troweled surfaces, apply DCI Hard-Troweled Floor Prep to insure a consistent acid stain reaction. Test by pouring water on the surface. If the water beads up on the surface for more than a few seconds, the concrete is too smooth to acid stain successfully.
Newly poured concrete should include less than 10% fly ash to insure a good chemical reaction with the acid stain.
Concrete poured with excessive water in the mix can create a thin, unstable layer of concrete on the slab surface. To test for instability, press the tip of nail into the concrete. If breaking or damage of any kind occurs, the slab must be profiled with a sander or buffer using a 60-80 grit sanding disc before staining.
NOTHING takes the place of pre-application testing, particularly if you do not know the history of your slab. Always prepare a test area on the slab intended for staining prior to beginning a staining project.
Step 2. – Choosing Acid Stain Colors – When acid staining concrete floors, take natural lighting into account when select a color (s). If you’re staining a basement floor with very little natural light, choose a lighter color like Malayan Buff or use the darker colors as an accent stain. Always keep your color scheme in mind. Exact color matches are difficult to achieve with acid stain so select a complementary color (s). Many customers select at least two acid stain colors for indoor floor applications.
Step 3. – Clean Well Before Starting – Concrete floors can have all kinds of unexpected contaminants. If you have multiple contaminants like paint, glue and dry wall mud, it might be better to sand the floor using a high-speed buffer and an 80-grit sanding pad. If you only have small amounts glue and paint, apply Bean-e-doo Mastic Remover and Soy Gel Paint Stripper to clean the floor. Remember to carefully clean the floor with DCI Concrete Cleaner and water solution before acid staining. Rinse thoroughly to remove residue and allow to dry. Invest in a wet-dry vacuum for staining concrete floors. It really does shorten the work time and make clean up much easier. If the concrete condition is more than you’re willing to tackle, consider applying a concrete overlay. It can be acid stained or integrally colored with concrete pigment and might just be a better option when the concrete slab is heavily soiled or has other problems.
Step 4. – No One Way: Spray the stain however you want to. There’s no hard and fast rule for application. Marbled and mottled effects are very popular for indoor floors. Here’s the most popular indoor floor application on our website.
Step 5. – Select a Sealer Carefully: Gloss is probably the most important factor when choosing a sealer for an indoor floor. High gloss sealers are very popular but do tend to show dirt more readily than satin gloss products. Solvent based sealers have a strong odor and if applied indoors, should only be used in well-ventilated areas. Special consideration should be given for basements floors, especially if seepage, high humidity or hydrostatic pressure is likely to occur.
All acrylic sealers require a concrete wax for maintenance. Wax and Floor Polish can be buffed and adds additional luster to the surface. Waxes should be re-applied once a quarter expect in high traffic areas where more regular spot waxing may be needed. Two sealers – 550 Waterbased Polyurethane and 777 Modified Acrylic Urethane – are no wax sealers. Both are excellent concrete floor sealers but will need to be sanded and reapplied after 5-10 years.
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