Buy Basicare Cooling Eye Masks - Basicare Hot/Cold Gel Relaxing Eye Mask Mini Cucumber. How-to-Use: To use cold, chill the mask in refrigerator for about 60 minutes or freezer for about 10 minutes. Never freeze mask solid. Then gently place on closed eyes. To use warm, warm the mask in hot water until desired temperature is reached. Do not heat it with oven, microwave or boiling water. Test temperature before applying to eyes.