In 1997 Farouk Shami was in Italy, watching a pizza crust bake. According to the CHI history page, the crust stayed moist under ceramic heat, and he wondered what that would do for hair. He went home and built the CHI Ceramic Flat Iron, which the company calls the first professional tool to use ceramic heat. Shami got to hair through a hairdresser's problem. He developed a severe allergy to the ammonia in hair color, was told to leave the profession, and instead taught himself cosmetic chemistry until he made an ammonia-free color called Sunglitz. He started Farouk Systems in Houston in 1986, and the company says he was also the first to use silk proteins in hair care, through BioSilk. That history is the quiet engine behind CHI Silk Infusion, a silk protein leave-in enriched with silk, wheat and soy proteins that you work through from mid-shaft to ends before styling. A leave-in this simple depends on one clear idea. The first grid is four leave-ins from CHI, and they overlap more than they compete.

The second group is the rest of the CHI shelf, and it starts with the iron that made the CHI name. The Original has 1 inch ceramic floating plates, a single preset temperature of 392 degrees with an on and off switch, an 11 foot swivel cord and dual voltage. That fixed heat is exactly why I like having the Keratin Mist nearby, a protein spray the brand says protects against thermal tools. The Argan Oil conditioner pairs argan and moringa oils with the CHI ceramic compound, and the brand says it is sulfate-free and paraben-free. Infra Shampoo is written for heat-styled hair and uses what the brand calls Cationic Hydration Interlink. A small tip: shampoo, then conditioner worked from mid-hair to ends, then rinse with cool water, as the label suggests, before any iron touches your head.

Grid three steps outside CHI for finishing oils and serums. Moroccanoil started with Carmen Tal, whose hair was damaged by a bad color process, and a Tel Aviv salon that treated it with an argan oil; she took the idea home to Canada, and the Treatment became the brand's first product. Gisou comes from Negin Mirsalehi, a six-generation beekeeping family and a bee garden in the Netherlands, and the first product was her hairdresser mother's honey hair oil. IGK takes its name from the first initials of its four founders, and the Cash In serum uses vegan silk extract and baobab oil. Color Wow was founded in 2013 by Gail Federici, a John Frieda co-founder, and Pop + Lock is an oil-and-serum blend that the brand says smooths and glosses wet or dry hair. If frizz is your problem, any one of these works as a hair serum for frizz. What I would skip is stacking all four on one head. Each is designed as the last step, so choose one per day.

Here is how it plays out on my own week. Silk Infusion goes into damp hair, a small amount, worked from mid-shaft to ends, before the blow-dryer or the iron. The Keratin Mist goes on when I know heat is coming. A drop of oil or serum goes last, on dry ends, and only one.