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Applying the Stain
Safety First! Remember to use goggles, gloves and a dust mask while working with concrete acid stain. A respirator may be required for applications with poor ventilation. The appearance of the finished product is very much influenced by the manner in which the acid stain is applied.
We recommend spraying the stain on the surface using an all-plastic pump sprayer. If a darker, more even tone is desired, brush the acid stain into the surface using consistent circular strokes. If using a brush, spray on a second coat to eliminate any brush strokes on the surface unless that is the desired finish. Though new concrete may not always require a second coat of acid stain, older concrete does require two coats of stain for complete coverage. For a more diffuse look, spray the stain onto the surface without brushing.
To produce a “marbled” effect, spray enough stain on the surface to allow the color to naturally run and pool in the lower areas of the slab. This technique is particularly effective on outdoor concrete slab as they are generally poured on a slope. Applying the Concrete Acid Stain with the sprayer nozzle close to the floor will also produce “pooling” effects whether indoors or out.
To produce a multi-colored effect with distinct areas of color, begin with your lightest color as a base coat. Base coat colors can either be a light acid stain color such as Azure Blue, Malayan Buff or one of the darker stains cut with water. Apply one heavy coat of your base color and immediately apply accent coats while the stain is still wet to encourage a more natural appearance on the slab. Continue to apply the lighter to darker colored accents until satisfied with the results.
If walking on wet acid stain, wear acid resistant spiked shoes, golf shoes or similar cleats to avoid leaving foot impressions on the floor. For a veined appearance, spray your secondary or “veining” color on the surface first. While still wet, feather the primary color into and around the secondary color allowing it to flow together at the edges. Be careful not to cover your secondary color completely especially if it is a lighter shade. Contact a Direct Colors decorative concrete technician for additional information on application techniques.
No two finished floors are exactly same as acid staining is an artistic process. Always complete small test patches on your surface or prepare sample boards to practice with the sprayer and determine which look you prefer. Each of our acid stain colors can be cut with water to produce an array of different colors and shades. Keep in mind if the water content is too high, the chemical reaction between the stain and the concrete will be significantly reduced and may not be strong enough to produce the desired color, especially on older slabs. We do not recommend cutting our acid stains by more than 4 parts water to 1 part acid stain. Some colors vary more than others when increasing the water content and many factors determine how dark the final stain color will be such as age of concrete, cement content and weathering.
As the acid stain dries, a chalky residue will likely form on the surface of the concrete and is a normal part of the staining process. Each stain has different activation times to fully color the concrete, generally from four to eight hours. However, the stains can be left on for longer if a darker color is desired.
Summer Tip: Hot, dry conditions can cause acid stain to prematurely dry before properly reacting with the concrete. For best results, dampen the surface (no standing water) before applying acid stain to concrete. Sealers should not be applied to concrete over 90°F. For outdoor projects, apply sealers either late in the evening or early in the morning when concrete temperatures are at their lowest.