Check strength, area, and contact time
A percentage printed on a label is useful only when it belongs to the exact item and is interpreted with the complete formulation and directions. Do not assume a lower-looking number guarantees comfort or that two acids at the same percentage feel identical. A toner may be left on; a peel may require rinsing after a specified time. Body formulas can differ substantially in intended area. Follow manufacturer directions for application, frequency, and avoiding sensitive areas. If you already have another acid step, decide which one would be replaced before adding lactic acid. The useful comparison is a clearly labeled format for a specific area, not the largest number of exfoliating bottles.