Blake Lively spent seven years "obsessively developing" her new business venture

The actress - who is married to movie star Ryan Reynolds - wrote on Instagram: "Ever since I was a kid, through adolescence, early adulthood, motherhood, work, personal life, whenever, wherever, the single most identifiable part about me has always been my personalit- no? Not my personality? Oh... My hair.

"It's my longest companion in life. For 36 years and counting. And like any relationship, it's healthiest when you take good care of each other. To love it well, I've found a system that has worked wonders for me, a hack of sorts through decades of working with the very best people in the industry, and silly amounts of trial and error. I spent 7 years (I know. It toggles between impressive and wtf took so long) obsessively developing every detail of my newest baby, @blakebrownbeauty (sic)"

Blake "loves design desperately" and she's admitted to having some very specific ambitions for her brand.

The Hollywood star explained: "I wanted it to be cleaner than the products I was using with great results so I didn't feel nervous sharing it with family. I wanted it to attempt to show how beautiful maximum sustainability can be. I wanted it to be vegan, cruelty free and formulated without sulfates, silicones, parabens, synthetic dyes etc.

"As someone who loves design desperately, I wanted it to look [stars emojis] stunning [stars emojis] on your shelf because that's valuable space in your home, it should be beautiful. I was uncompromising on achieving all of those things at once. (sic)"