Will paint go through a canvas drop cloth?

Paint can go through a canvas drop cloth depending on canvas weight, treatment, and amount of paint, so protection level varies. Standard cotton canvas drop cloths, such as 8 ounce or 10 ounce untreated canvas from hardware stores, are absorbent and will soak up small drips and splatters, preventing them from reaching floor for light painting, but heavy spills, pooled paint, or prolonged wet paint sitting on thin canvas can seep through to floor, especially if canvas is thin or worn. Heavier canvas like 12 ounce or double layer provides more protection. Some canvas drop cloths are treated with butyl rubber or plastic backing on one side, called rubber-backed or leak-proof drop cloths, which prevent any paint from bleeding through and are best for hardwood floors and carpets. To prevent bleed-through with regular canvas, you can double up layers, use plastic sheeting underneath for extra protection, and clean up spills quickly rather than letting paint pool. For art use, unprimed canvas drop cloth will absorb paint and paint will go through to other side unless primed with gesso. So regular canvas drop cloth resists light drips but will allow heavy paint to go through, while rubber-backed canvas prevents bleed-through and is recommended for full protection.