Then I recalled something Pung had said: "Some chefs apply things on the skin—salt, lime juice, baking soda, maltose—to make it more crispy." Acid, alkaline, and alcoholic ingredients all help to denature the skin proteins, disrupting their physical structure and loosening them up, which promotes blister formation and browning. From past failures, I knew that sugar, vinegar, and condiments like soy sauce gave me poor or patchy results, but recipes that used a rubdown of gan sui, or alkaline water, a solution of sodium and potassium carbonates, usually achieved a high degree of puff. But I didn't like the soapy, bitter aftertaste the gan sui left. I knew I would have to come up with another method.