I’ve been known to hold up slides, filmstrips, and negatives to the light; I check watermarks in money and on letterhead in the light, but it’s not often I stare at letter openers, teacups, or postcards under the scrutiny of a 100-watt bulb. There’s hidden images in more places than most people realize, although most are rare, and not easy to recognize right away.
Stanhopes are a mid-19th century novelty which take their name from the inventor who developed their main component. Lord Charles Stanhope lived during the 18th century and developed a tiny magnifying lens; its drawback is that the object to be magnified must be touching the rear surface of the lens. Enterprising photography experimenters discovered that a short Stanhope lens could display a tiny microfilm image if the little picture were glued to the reverse end of the lens. The magic of the optics science aside, this invention created a novelty market, in which tiny lenses and photos were embedded into jewelry, collectibles, statuettes, and anything else they could mount it into. A majority of stanhopes were not obviously a stanhope from the outside, giving them a magical quality that entertained Victorians to no end. The images varied from basic art, to souvenir images of a World’s Fair or tourist attraction, and — of course — naughty images found their way to the insides of thes tiny private viewers. Crosses and rosaries with a stanhope of the Lord’s Prayer were quite common in the past, and you can still buy a similar pendant today – and even get modern stanhopes made with your own pictures.
Hold-To-Light postcards are a surprise prize for collectors; it might even be possible that you have one and don’t know it. Popular in the late 19th century, hold-to-light postcards were made by sandwiching layers of cut and printed paper, resulting in an outside that looks one way in normal light, but by being illuminated from behind portions of the ‘sandwiched’ layer will be visible. The process was quite elaborate for the manufacturing skills of the time, which make them all the more amazing today. Many are simple ‘die-cut’ cards that have thinner parts which will appear lit when illuminated from behind, such as the windows of a building or a flame on a candle, giving the card an extra layer of visual appeal. Others, my favorite, have a ‘transparency’ section, different than what we’d call a transparency today, which relies of a complexly designed interior layer, which can add to or completely change the image when held up to the light.
Lithophanes take this art form to an amazing degree. One identifier of fine china is to hold it up to the light and see how much light passes through the porcelain: the more, the better. Lithopane uses that quality of porcelain (or wax, or any other translucent substance), and adjusts the translucency to show an image in full grayscale. The see-through postcards operated similarly on a very basic level, but the quality of the lithophane could be amazingly high when done by the hand of a master craftsman. Lithophanes were often built into lanterns or candle holders, to create an illuminated image when the light was lit, artistically brightening the dark of night. Creative ceramics manufacturers ‘snuck’ lithophane images into other products, though, most notably Chinese tea sets. The bottom of the teacups — possibly only a select few in the set — would be embossed in such a way that, when finishing your drink, you could catch a glimpse of a geisha girl image in the bottom of the cup held to the light.
Hidden images could turn up anywhere, from in the tiny aperture of a doll’s telescope, to the bottom of a teacup, so next time you see me holding up a silver trinket in front of a display light, don’t think I’m crazy: I’m just looking for the secret pictures.