24 Hr Nutri-Serum. Seaweed-Extract and Collagen. Noticeably firmer skin in 2 weeks. Dove Intensive Firming Lotion contains a unique seaweed-extract combined with Collagen and Dove's active moisturizers. This unique formula significantly firms skin and increases skin's elasticity. Seaweed-Extract is known for its firming action and is commonly used in spa firming treatments. Collagen is known for its skin firming attributes. Dermatologist tested. Tests Prove: After 1 week your skin feels significantly smoother and appears more youthful. After 2 weeks your skin is noticeably firmer.