Caps have hair pulled through at random, typically using only one color to hi-light. This should only be used with shoulder length or less hair. Foiling is more precise, weaving hair exactly where and how much. Several colors can be used easily with foiling. A more natural effect will be achieved with foils also allowing more time between touch-ups since the color can be applied more closely towards the scalp. Foils are used with "Blocking" color, "chunking" and dimensional hair coloring.