Type 4 hair can range from fine and thin to wiry and coarse with lots and lots of strands densely packed together. Coily hair has fewer cuticle layers than any other hair type, which means that it has less protection from the damage inflicted by combing, brushing, curling, blow-drying and straightening.
Type 4a is tightly coiled hair that has an "S" pattern. It has more moisture than Type 4b coils and has a visible curl pattern. The circumference of the spirals is close to that of a crochet needle. The hair can be wiry or fine-textured. It is usually fragile with high density. Type 4a hair has fewer cuticle layers than other hair types, which means it has less natural protection from damage.
Type 4b strands have a "Z" shape and a less defined curl pattern. Instead of curling or coiling, the hair bends in sharp angles like the letter "Z." Type 4b hair is tightly coiled and can feel wiry to the touch. Type 4b hair can range from fine and thin to wiry and coarse with many strands packed densely together. This hairtype often experiences shrinkage up to 75% of its actual hair length. Type 4b coils can hold altered styles well in comparison to Types 2, 3, or 4a hair.
Type 4c hair is composed of strands that will almost never clump without the use of styling techniques. Type 4c hair can range from fine, thin, soft to coarse with densely packed strands. Some say Type 4c coils look identical to 4b except that the curls are tightly kinked with less definition. Tighter coily hair can shrink more than 75%.