Type 4 hair is the kinkiest of all the hair types. People with this hair type are more likely to deal with dryness and shrinkage. 4A hair features spirals that are a bit smaller than 3C curls, while 4B strands are bendy and Z-shaped. 4C hair has sometimes been characterized as not having a defined curl pattern, though it's pretty similar to 4B hair. The major difference between the two is that the curl pattern of the former is slightly tighter, causing it to shrink more when wet and making it more difficult to detangle.
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