Complex sentence: Car paint alone would be unsuitable for human nails, as its brittle formula is designed for the rigid surface of a car; its formula has been revised repeatedly in order to prevent the cracking or flaking that occurs with the natural movement of the nail.
Split into simpler sentences: Car paint alone would be unsuitable for human nails, as its brittle formula is designed for the rigid surface of a car. Its formula has been revised repeatedly in order to prevent the cracking or flaking that occurs with the natural movement of the nail.