We used the rock salt technique on a regular basis down in the Disney Theme Parks. It included broadcasting a light or medium rock salt over the surface about the time that you would consider stamping it (depending on the texture) and then covering over that with a thin mil plastic, typically 1 mil. We would purposely not have the plastic lay flat, but with creases and folds in it. We would then tap the rock salt into the fresh paste with our pool trowels and then literally trowel the thin plastic into the surface of the concrete. The plastic acted as a lubricant for our trowels, while at the same time producing an interesting texture. We immediately removed the plastic and then cleaned either the next day or several days later; by then the rock salt dissolves. A word of caution -- rock salt is probably not the best finish in freeze thaw environments because moisture can get trapped in the low lying areas, freeze and promote pop-outs. However, the plastic finish is a wonderful non-skid surface that produces a leathery-like look after the staining process.
The seamless texture surface is a wonderful candidate for acid staining because the stain concentrates in the low lying areas of the texture, producing a very natural look that mimics natural stone. Experiment with the appropriate texture in the given area (i.e., interior residential floors vs. sloped driveways).
One of my favorite textures for staining happens to be the rotary sweat finish. This is simply taking a pool trowel at the last phase of troweling and in a circular pattern, rubbing the trowel flat as opposed to cocking the trowel as if you were final troweling. This is a wonderful nonslip surface especially for exterior applications, and the stain looks beautiful on this finish.
The bottom line is if you are the contractor who is actually installing the concrete with the intentions of staining later, it is your responsibility to understand the mix that you are pouring as well as the influence, or the texture, you are putting on the surface when you come back and stain. I encourage you to experiment with these different textures.
All the best!
Bob Harris is the founder and president of the Decorative Concrete Institute, Temple, Ga., which provides hands-on training in architectural concrete. He has personally placed or supervised the placement of more than 3 million square feet of decorative concrete and is the author of a best-selling series of decorative concrete books and DVDs. For more information, call 877-DCI-8080 or visit decorativeconcreteinstitute.com.