"Reading after dark has lost a bit of its wonder. In the era of tablets, there’s no need for kids to rebel in the nerdiest of ways, stashing contraband flashlights in order to sneak some reading under their blankets after bedtime. iPads have blindingly bright backlights built right in. But a brilliant new book Hide & Eek!, by Rebecca Sutherland, Hat-Trick andKnock Knock, wants to bring some of that special experience back. It’s a book with a fun twist: The exciting and scary images are hidden during the day, and will only appear under a flashlight at night. “It’s magical then when images appear that cannot be seen with the naked eye,” explains Hat-Trick’s Creative Director Jim Sutherland. “Even when you know how it works, it’s still amazing.”

And it really couldn’t work more simply. Ink is essentially sandwiched between two fused sheets of paper, so it only appears when the page is lit. Of course, Sutherland admits that this is easier said than done: The tricky part was making the effect completely invisible during the day, which required testing various papers and tweaking the tonal range of the illustrations until they found the magical sweet spot.

But that sweet spot must be delightful in person. Lions, elephants, and monsters appear to fill the blanks in innocuous illustrations, proving that good old analog tricks can still be fun and relevant in a world dominated by digital UIs. Plus, now that the team behind Hide & Eek! has their print methodology down, they plan to release several more books in the series, transporting kids under the sea and into the jungle, all from the cozy safe haven of their own beds."

(via FastCoDesign)