Forget balayage for sun-kissed colour, the 90s way to achieve natural-looking highlights was a colourful plastic bottle full of peroxide. Sun-In gave a generation of teenagers their first experience with going blonde – or attempting to. The science behind Sun-In is nothing new; people have used the bleaching effects of the sun to lighten their hair since ancient times. There are countless examples of cultures applying chemical solutions to their hair before lying out in the sunshine with the sole aim of going blonde – with Romans and Renaissance Venetians in particular being obsessed with achieving highlights using fairly similar DIY formulas. Sun-In was patented in 1987 – not in California or Miami, but in Chattanooga, Tennessee. The peroxide and lemon spray – activated by the sun’s rays, just like its ancient forebearers – made sun-kissed highlights accessible; although anyone who was too overzealous with the spray, or whose hair didn’t lift quite so easily, can attest to results that were more patchy, dry and orange than beautifully natural.