An acid stain is a transparent concrete stain. In other words, you can see right through the color.
You will still be able to see all the characteristics that existed before the stain is applied. In fact, acid stain will enhance the appearance of any variation within the surface of the concrete itself. Think of it just like stains used for wood. It doesn't hide any of the grains or natural characteristics of the wood. It does quite the opposite and brings out the natural uh traits of the wood. Concrete, like wood, has an inherent beauty that is brought to life with acid stains.
Unlike acrylic stains, paints, and sealers, an acid stain is not a coating by any means. It will not fill in any of the pores or prevent penetration of any substance into the surface. Acid stains actually etch the surface as they color it, which increases the porosity of the concrete. This is one reason why it's important to apply a sealcoat after using a transparent concrete stain.