It is not unusual to have variations in the tone of color for shotcrete or concrete walls that have been stained due to variation of the texture or density of the surface being stained. An acid-based stain typically results in more consistent shading. When anticipating that a wall will be stained, extra care needs to be taken in the curing process. It is generally recommended that walls to be stained should be water-cured to avoid any interaction between a curing compound and the stain material. If a curing compound is used, it must be completely removed prior to applying the stain material. Consult the stain supplier for more information.