✅ Quick Answer Heat tools plus summer sun and humidity dry out hair and roughen the cuticle. A leave-in keratin lotion helps it recover: it stays on after washing, adds lightweight conditioning, smooths frizz, and protects the cuticle. Apply to damp mid-lengths and ends 2 to 4 times a week and ease off the heat. It will not undo damage overnight, but consistent use keeps hair softer and smooth …