Concrete is naturally porous. Depending on how it’s made, it can hold 5% to 20% of its weight in water, making it effectively a stiff sponge. When something is spilled or rinsed with water, staining and discoloration can occur. Spills, like oil, seep into the concrete pores, and while the surface can be wiped clean, what’s in the pits and pores remains. Hosing down the surface may solubilize the dirt on top, transferring it into those hard-to-reach low areas.
Blotting spills instead of wiping them is recommended unless the floor is sealed or coated. Power washing can help but won’t fully restore the original appearance or address the root cause—those open pores. To maintain clean concrete, it’s best to seal or coat it. Sealing fills in the pores, so dirt remains on the surface and can be easily cleaned. However, spills left to dwell may still seep through. A coating offers a more consistent barrier and can also enhance the floor’s appearance.