With a touch, this spell causes a small, rapidly growing patch of corrosive acid to appear on the target. On the first round, the acid deals 1 point of acid damage per caster level (maximum 15). On the second round, the acid patch grows and deals 1d4 points of acid damage per caster level (maximum 15d4). On the third and final round, the acid patch covers the entire creature and deals 1d6 points of acid damage per caster level (maximum 15d6). The target can spend a full-round action to scrape off the acid, or can wash it off with at least 1 gallon of liquid to halve the damage for that round and negate the remaining rounds of the spell.