You may need to find a way to heat it- stick it by a sunny window or something. Do not put anything over it until it is thoroughly dry. I love Testors enamels, but they are slow drying. And, they go bad sooner than most other paints. If there is any question in my mind about an old bottle of paint I pitch it in the trash. I also built a homemade drying box, using a 60 watt incandescent bulb as a heat source. It works great, runs about 105 degrees and cuts drying time down to a day or less instead of several days.