Readers within the age range of 25-35 might remember Hypercolor or Hypergrafix clothing,* the color-changing T-shirts produced by Generra that were all the rage in the early ’90s. Now that the ’90s are back and high-end Hypercolor-esque items are popping up everywhere (for example: scarves from LA-based Anzevino and Florence, T-shirts and denim shorts from British designer Henry Holland, T-shirts from American Apparel, and sneakers from Puma), it might be a good time to finally figure out the science behind the color-changing clothing.
How Does it Work?
The secret to Hypercolor shirts and products like them is thermochromism, the ability of a substance to change color due to a change in temperature. The shirts are manufactured with two dyes: one regular dye that provides the constant “true” color of the fabric, and a thermochromic dye enclosed in microcapsules bound to the fabric’s fibers. The thermochromic dye is usually a mixture of a leuco dye (a dye whose molecules can take on two forms, one colorless; Hypercolor shirts often used crystal violet lactone), a weak acid, and a dissociable salt dissolved in the fatty alcohol 1-dodecanol.
At low temperatures, the dodecanol is solid and the dye exists in its colorless leuco form. At warmer temperatures (>75.2 °F), the salt dissociates, the pH is lowered, and the dye’s lactone ring opens, allowing the dye to become colored, producing a color change in the warmed area. The new color is dependent on the combination of the color of the fabric and the color of the non-leuco form of the dye—so blue fabric and yellow leuco dye make for a green warm spot.**
More Than Nostalgia
Leuco dyes and other thermochromic applications, of course, have many uses beyond novelty T-shirts. Leuco dyes are used on Duracell batteries along a resistive strip to indicate their heating and gauge the amount of current flowing through it. Thermochromic dyes are also used on food vessels to indicate the temperature of their contents, or monitor their time-temperature storage history. They’re also used in building materials, where solar heat turns the material white and results in the reflection of solar radiation and maintenance of the building’s temperature. Other thermochromic materials are used in thermal sensors designed for immersed applications, like in fish tanks or washing machines.
* I don’t remember the Hypercolor fad, as I was a chubby, Batman-obsessed grade-schooler with coke bottle glasses during the early 90s, and recently had to have editor Jason explain it to me.
** Sometimes, the opposite effect, where the thermochromic dye changes from its colored to non-colored form in response to heat, is desired. In these cases, phenolphthalein, thymolphthalein or other compounds that are colorless in acidic ranges are often used.
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Amazing. Just last weekend, my son and daughter were visiting and we were talking about the ‘cool’ color changing shirts they used to have.
posted by old hippy chick on 4-24-2010 at 11:05 pm
i foresee one problem. how many people are gonna go around with their armpits a different color than the rest of their shirt?
posted by CKH on 4-24-2010 at 11:07 pm
Does anyone have a picture of themselves sporting a Hypercolor shirt? If you do, and you’d LOVE to see that plastered all over our little corner of the web, send it to jason@mentalfloss.com.
posted by Jason English on 4-24-2010 at 11:19 pm
These shirts were right up there with Vision Street Wear (I was a skater back then): things that seemed really cool if you were twelve, but by the time you were sixteen you started to realize how stupid they actually looked.
Vision Street Wear was way worse, though. Vanilla Ice-lookin’ crap.
posted by clint on 4-24-2010 at 11:35 pm
That was not a good look either for females wearing a tank made of the stuff…especially when we were with a somewhat fresh idiot who couldn’t keep his hands to himself.
posted by Tink on 4-25-2010 at 1:30 am
I’m 45 and I remember Hyper Color – I even bought one, they were available in the later 80′s actually.
Don’t know why anyone thought they’d succeed at this, the shirts looked like they were washed 25 times then sold as new.
posted by Dianne on 4-25-2010 at 1:34 am
Doesn’t black absorb heat and not reflect it?
posted by infomantic on 4-25-2010 at 2:01 am
I didn’t like HyperColor, but loved Freaky Freezies, I could see those coming back.
posted by Jamie on 4-25-2010 at 9:12 am
“They’re also used on building materials where solar heat turns the material black and results in reflection of solar radiation and maintenance of the building’s temperature.”
Turning the material black would make it absorb solar radiation, heating the building. This would be useful in the winter, but bad during the summer.
posted by Ben on 4-25-2010 at 9:47 am
I would never buy that. I can just see myself with bright rings under my armpits and, in shorts, bright coloured crotch area. Not good, not good at all!!
posted by Ciel42 on 4-25-2010 at 10:45 am
I remember wear one of those to a dance in high school. I had bright pink boobs and the rest of the shirt stayed purple…..Lovely…
posted by Eden on 4-25-2010 at 11:53 am
Oh yeah, and lets not forget people trying to leave hand prints on certain parts of your body….I can’t believe that crap is coming back…..ugh
posted by Eden on 4-25-2010 at 11:55 am
You can still buy hyper color stuff – just go to the caribbean – you can get them at almost all the tourist shops. Both solid shirts and then shirts that start out as white and then when they get warm a design (typically with fish on it) shows up.
posted by Beth on 4-25-2010 at 1:42 pm
oh I LOVED my Hypercolor shirts! I am am older than 35 thank-you-very-much. I was a freshman/sophomore in high school when they were in. I had a pink one and also a burgundy one. And yes, I remember when people would try to make hand prints in “fun” places.
posted by Angie on 4-25-2010 at 10:03 pm
Don’t forget the color changing Hot Wheels! Dunk them in cold water and they change color, and then the metallic surfaces start getting gross!
posted by Rajiv on 4-26-2010 at 8:31 am
Wow I knew so many people with these shirts. I never owned one though. Too many were ruined after they washed them once – what a waste.
I wish the bad clothing fads would stay in the past.
posted by Christina on 4-26-2010 at 8:31 am
I was in middle school when these were popular. And like some have said, I remember there being backlash because they were so popular with the puberty-set, and the areas in the armpits and on the breasts would change color, drawing attention to them.
posted by Amy D on 4-26-2010 at 10:30 am
Oh, awesome! I lurved Hypercolor shirts but never actually owned one.
I get that it was/is a really bad, impractical idea…but still! Clothes that change color! Awesome.
I’m with Jamie, though — bring back Freaky Freezies!
posted by Jen on 4-26-2010 at 11:06 am
I totally had a Hypercolor shirt, which was a really bad idea for a girl who was always a bit sweaty from skateboarding in middle school. :(
@Clint: Vision Street Wear rocked! I think everything I wore during my skater phase was VSW.
Next we’ll be hearing that Z-Cavaricci, Forenza and Outback Red are making a comeback…long live the 80s!
posted by Corinne on 4-26-2010 at 11:37 am
Remember all those things that changed color to show they were hot like mugs that showed secret message when hot liquid was pour into it or hot rollers that went from blue to white to show they were ready.
They mugs were permanently in the “hot” position if they were washed in the dishwasher and my color change hot rollers are now permanently gradient white to blue regardless to how hot they are.
posted by lewen on 4-26-2010 at 2:44 pm
I had a shirt with color changing flowers on it when I was nine. Then we brought my newborn sister home from the hospital and she peed on my shirt on the way to the bath. It changed the colors and they never went back!
posted by Mandi on 5-4-2010 at 2:32 am
does a patent exist for hypercolor and if so can i buy copyrites?
posted by brian mcinnis on 8-1-2010 at 8:52 am