Many years ago I remember seeing something on TV about a special glass, and a particular printing technique, whereby you could print a basic image on one side of the glass, but from the other side of the glass the glass would appear completely transparent and you would have no idea that there was an image on the other side.
But…I’ve Googled around recently and found nothing. Did I dream it? Was it a hoax? It does sound like an April Fool-type thing, doesn’t it.
Anyone know anything more (obviously you can’t know if I dreamt it, but you may know if it’s real or a hoax)?
Can’t help much with the details but i can at least can confirm you weren’t dreaming, i remember seeing that too, Tomorrows World maybe?
Buses up here often have full side adverts that cover the windows too. It’s not completely transparent but it’s just plain grey from the inside and doesn’t impair vision much. From the outside it’s full colour and looks solid although up close you can see it’s actually a dot print with spaces between.
I can’t remember the programme well enough to know if this is the same thing.
It certainly was on Tomorrows World! IIRC, it was up for a Prince of Wales award as well.
Yes, that’s the same thing. The original product was Contravision perforated film, but they have developed unperforated products with a far smaller dot size.
There was a kid I knew in elementary school that had a pair of sunglasses with something printed on the lenses (I think they were baseballs or something) that, from the front, completely obscured his eyes. I remember being amazed when he let me try them on and I could see through them as though they were just normal sunglasses. Perhaps this is the same sort of thing?
I can’t tell if this is what you’re looking for either, but you see them a lot in the south – giant decals that take up the whole of a truck’s rear window.
I’ve never had a look at those from the interior side, so I don’t know if you can see the design looking out or not.
On edit, I’ve been beaten to the decals!
It’s funny really, I’ve seen the phone boxes and buses and things but never really connected it with the memories in my mind. I guess because the technology when presented on TV looked perfect: a solid image versus colourless, totally transparent glass on the other side.
But I suppose regular, low-definition TV, isn’t sensitive enough to show that the effect is not perfect.
Not quite the same thing, but I once heard UT Theater professor David Nancarrow describe his technique for using aniline dyes to color one side of a scrim drop (I think he said he just used burlap) and some other process (I forget what) to color the other side. From the audience you saw a different image depending on which side of the drop was lit. Like an ordinary scrim, it was also more-or-less transparent if you only lit the scenery behind it.
I think you could do the same with ordinary scrim material, only I think it’s kind of expensive to use that way. (He got the burlap cheap.)
Just to be clear about something, it would be absolutely impossible to make something that has a different transparency in different directions, without some sort of external power source. If something passively allows exactly 50% of the light hitting it through in one direction, then it’ll also allow exactly 50% of the same sort of light through in the other direction. Anything else would violate the second law of thermodynamics.
I suppose you’re right. But what a theatrical scrim does is create the appearance of changed transparency by altering the signal to noise ratio. The scrim appears opaque when lit from the front because the reflected light washes out any light that comes through from behind. When you remove the front light and bring up the background lights, the eye quickly adjusts so it can perceive the scene behind almost as if the scrim wasn’t there.
I believe Nancarrow’s trick employs the difference between transmitted and absorbed color. When you light the back of a dyed scrim, the dye colors the light that’s transmitted forward to the audience. Opaque coloring brushed lightly on the front surface would attenuate the light from behind, but it doesn’t contribute any color. When you light the front of the scrim, the opaque coloring reflects its colors to the audience, more or less blocking the dyed image.
To get the most convincing effect, I think you’d have to paint the entire front surface as lightly and evenly as possible, but not leave any unpainted surface. That way the dyed image would be transmitted forward evenly across the scrim.
Most bus windows are pretty heavily tinted anyway (at least in my town), so you don’t really lose much outward visibility if instead you lay a colored scrim over the outer surface.
