For all of you seasoned DIY hair dyers, we'd be willing to put money on the fact that you've noticed just how soft and shiny that complimentary sachet of conditioner leaves your hair. Are we right?
It turns out that the internet has too.
In fact, one Reddit thread is dedicated to the question: 'What is in box hair dye conditioner that makes my hair so smooth, silky, and shiny?'
Even the celebrities are at it.
See: Hair Colour Ideas - Shades To Try
Christina Hendricks, actress, hair chameleon and spokesperson for Clairol's Nice 'N' Easy, told The Cut: 'I save them for as long as I can after I colour my hair because they are the best and really nourishing...'
So what is it that makes it so special? We've got some answers for you.
Speaking to Allure, Cosmetic chemist Randy Schueller says the magic ingredient is bis-isobutyl amodimethicone.
Sound like a bit of a mouthful? It's a silicone that's included in the formula, which is 'rated as a more intensive conditioning agent'.
Randy goes on to explain, 'Most conditioners don’t use such an intensive conditioning agent at such a high level. That's probably what makes this product so special'.
It looks like Nice 'N' Easy are selling 'in-box' conditioners separately, although it's not clear if this magic ingredient is included.
Of course, there are a number of home dye brands to choose from, most with their special conditioning sachet.
Anyone else thinking of stocking up on box colours?