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arnbev959's avatar

Blackened Sales Receipts and Glowing Scotch Tape.?

Asked by arnbev959 (10852 points ) December 30th, 2008

I was in my room last night with the door shut and the lights off and the blinds closed, playing around with some film and old cameras. I cut up a roll of film, and I was going to tape it inside the camera. I took a roll of scotch tape, and pulled a piece off, and lo and behold, I saw light. At first I thought there was someplace where light was getting in my dark room, and I had moved the tape in front of the light source, which reflected on the tape. But after a look around I couldn’t find any place where light was getting in. So I continued. I pulled another piece of tape off, and I saw light again! I figured it was just a hallucination, but the next time I took a piece of tape I watched it, and it glowed. It was a greenish, eerie sort of glow, produced right where the tape comes off of the roll whenever I pulled at it.
Why on earth does this happen?

After I was done with the cameras for the night I went downstairs and sat by the wood burning stove. The pyro that I am, I naturally started looking through my pockets for something to burn. I found a sales receipt from Stop and Shop. I tore off a corner of the receipt and placed it on top of the stove, and watched it start to blacken. I picked it up after it was sufficiently darkened, but to my surprise, the other side was still white! I tried it with the rest of the receipt. Only the side with the printing on it changed color. It wasn’t burning, as I initially thought. There must have been some chemical reaction going on with whatever kind of coating is on the surface of the receipt.
What is on sales receipts that causes the one side to turn black when heated?

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25 Answers

DrasticDreamer's avatar

I don’t know why the tape glows, but I know that a lot of stores now use the thermal printing method because the receipts print faster, give you the option of “branding” a logo onto the receipt and sometimes it’s simply cheaper than other methods.

I looked up what is specifically on the receipts and it’s generally…“a combination of a fluoran leuco dye and an octadecylphosphonic acid…” – from Wiki.

tinyfaery's avatar

Wow. Are you stoned, or is it me?

simpleD's avatar

Scotch tape has been found to emit X-Rays in a vacuum. But this study doesn’t mention visible light in air.

I’ve developed hundreds of rolls of medium format B&W film in the darkroom – pitch black. I was always amused by the sparks of light that came from pulling the end of the film off the tape that connects it to the spool. It never seemed to be enough to fog the negatives.

Your receipts must be from a thermal printer. The print heads produce spots of heat to darken a chemical on one surface of the paper. Fax machines use this frequently.

Foolaholic's avatar

Props for finding this all in one night!

lrk's avatar

@tinyfaery: did you see his username?

asmonet's avatar

McDonalds receipts do that all the time. Sometimes if you leave the receipt with the food in the bag for a few minutes the heat will blacken the paper with odd scorch marks.

No clue about the tape though.

richardhenry's avatar

@irk And avatar?

peedub's avatar

I smell Nobel Prize.

I love the part that goes “I figured it was just a hallucination…”

augustlan's avatar

…like it’s no big deal!

loser's avatar

This made me feel stoned even though I’m not!

Foolaholic's avatar

@loser

agreed. I kind of want to spring it on people the next time we get high, and see what people do…

loser's avatar

heh! heh! cooooool!!!

El_Cadejo's avatar

Holy glowing scotch tape Batman!

Sooooo i just got some tape and turned off the lights, it glows green. Pretty spiffy. Hmmm i really hope we can get an answer for this.

then again it is called Scotch Magic Tape….

richardhenry's avatar

Hah, X-Rays deal. Free X-Rays with your Scotch tape!

El_Cadejo's avatar

ya know, it may just be me, but scotch “transparent tape” doesnt seem to light up as bright as “Magic Tape”

richardhenry's avatar

Well it’s not magic is it, stupid.

El_Cadejo's avatar

i figured out the best way to make it light up is put the roll on your finger so you are looking down onto the side of the roll. Then give it a quick tug and you should see a streak of light go across the whole roll.

asmonet's avatar

Questions don’t end in full stops, Richard. Do they?

stupid.

richardhenry's avatar

Nut sack. :(

Harp's avatar

The effect that produces the Scotch Tape glow is called triboluminescence. It occurs when positive and negative charges are separated, which in this case happens as the adhesive releases from the mylar substrate of the tape. This creates an electrical potential and an air gap between the two charges. Electrons from the negatively charged side will jump across this gap to the positively charged side, and in the process will collide with nitrogen atoms in the air there in the gap. This produces light with the same spectral components as lightening, mostly UV but with a small component in the visible blue range.

This is the same phenomenon that causes the glow when wintergreen LifeSavers and sugar cubes are crushed, and when diamonds are cut. In all these case, you get the same spectral fingerprint.

andrew's avatar

Wow, that just answered my question about lifesavers!

wilma's avatar

I actually did hallucinate about Scotch tape once, but that is another story.

Thank you @Harp that was very informative and cool.

Zyx's avatar

This is the kind of technology I love. So simple yet so farfetched.

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