The first day I went to barber school in 1980’s, my Dad, who was a classically trained barber born in the 1950’s, gave me these words of haircutting wisdom: Always remember – when you cut hair evenly it will lay like shingles on a roof. His best advice applied to the shorter, clipper-cut styles popular during his time, however, it produces the best possible results with the longer, scissor cut hairstyles common today.
To portray this shingles notion, we’ll assume you’re giving a haircut to someone with straight or wavy hair. Once a handful of 1,000 hairs (give or take a few hundred) are cut, and the holding hand releases them, the cut hairs bend back into a lying position.
A long, layered cut has gradually increasing length around the sides and back. The shingles principle still holds, but the hair ends lie farther from each other than they do with the equal-length cut.
When hair is cut to lie like shingles, those hairs are able to lie in any direction and they still have their shingles nature. (The exception to this rule occurs when straight hair is bent against the hair grain: then the hairs stand out instead of lie down, but at the first opportunity they will return to a more comfortable lie down position.) The fact that those hair ends always blend in with their neighbors is the thing that makes these haircuts so carefree–be it windblown, handcombed, or whatever, it still goes back to lying like shingles on a roof.