Three possibilities here:
The simple to implement printed message on the inside of the packet. Once torn, the packet has to be fully squeezed out and then fully "opened" to see the message.
The more complex mechanism would rely on a chemical reaction of some sort that would be triggered when the packet is opened and would display the message on the outside of the packet.
And, the 3rd way as suggested by st3f's anno-- theircompetitor, Apr 16 2004 In-baked Fortune Cookie http://www.halfbake..._20Fortune_20Cookiein the same vein [FarmerJohn, Oct 04 2004] Clear plastic foil http://en.wikipedia...cy_%28projection%29 [spidermother, Dec 24 2012] Third possibility: Print the message on the inside of the sachet with a clear window facing it. Only works if the contents are opaque.-- st3f, Apr 16 2004 What st3f said.-- jutta, Apr 16 2004 thanks, st3f, jutta -- great suggestion-- theircompetitor, Apr 16 2004 Reminds me of prize messages printed on the interiors of soda cans.-- DrCurry, Apr 16 2004 Look around for "Duck Sauce" packages (single serving size) in Chinese restaurants. I once saw a brand where the sauce was in clear plastic foil package with a printed logo on each side. The logo showed a smiling lady. When the package was empty you could see through so both were logos overlaid. When you rubbed the empty package just right, so the two walls moved against each other the figures would do XXX rated things with each other (took some imagination, but kids have a lot of that).-- kbecker, Apr 16 2004 // sauce was in clear plastic foil package... //
I didn't know we had that technology. Plastic foil?-- waugsqueke, Apr 18 2004 Not a bad suggestion, but there would be a lot of frustrated and lazy people that wouldn't bother with all the mechanics necessary just to read something irrelevant and not in any way accurate.-- kranedawg, Apr 19 2004 <Fortune message inside McDonald's Condiment Packet> You will be fatter by the end of the day <Fortune message inside McDonald's Condiment Packet>-- Pericles, Apr 20 2004 //We don't have a cow that is also a sandwich//
Thanks, that's a great line for my next VC pitch-- theircompetitor, Apr 21 2004 Ha, clear plastic foil, that's an idea.-- blissmiss, Dec 24 2012 "A transparency, also known in industrial settings as a "viewfoil" or "foil", is a thin sheet of transparent flexible material, typically cellulose acetate"... (link).-- spidermother, Dec 24 2012 Why not carefully pack the contents using pigmented condiments that spell out the message as applied? That would be an attractive novelty and would encourage use of more product, as the full contents of the packet must be squeezed out to reveal the entire message. The R&D would quickly pay for itself if only there were a single-serving condiment packaging firm with the cojones to pursue this technology.-- Alterother, Dec 24 2012 random, halfbakery