Acid staining...
Acid stain may be applied with a sprayer or a paint brush. An alternative to acid would be to add pigment to the concrete while in the cement mixer, or dust it on the floor while the concrete is still wet.Floor, p5
Acid Staining
Once the walls and roof were in place, but before interior plastering commenced, the floor was acid stained. This process requires a floor free from grease or other impurities that might repel the acid and render an unsatisfactory finish. Be sure to wear gloves, a mask, and eye protection, as the acid is corrosive.
Initial application of acid stain. Additional applications will deepen the color.
I used three different colors of stain, two shades of brown, and one of green. After cleaning the floor with a mop and water as best I could, I let the floor dry and vacuumed it. Next I began to apply the stain with a paint brush, though it may be sprayed on as well. (Note: first it is desirable to test a small area in an inconspicuous place to determine if the stain will take and if the color is what was expected.) I varied the application of the three colors to try to achieve a more natural appearance, and used a circular motion, as recommended by the manufacturer, to better conceal any brush stokes. Apply a generous coat of stain, but don't let it puddle. As the stain dries it changes color, and its final color will not be apparent until it has dried and then been mopped with a water/ammonia solution to neutralize the acid. A second mopping with clean water will yield the final appearance. To darken the floor, repeat the entire process. If a lighter color is desired, cut the stain with water prior to or during application. Once the floor was mopped and dry it was ready to be grouted (coming soon). For now, on to setting the posts and beams.