Ask A Scientist Chemistry Archive

(Created prior to 1993)

Question: A student of mine is conducting an experiment on Hypercolor T-
shirt.  He is investigating the parameters under which the t-shirt will not 
change the colors.  He is also trying to investigate the optimum conditions 
under which it works.  Any help in obtaining research materials and ideas will 
be appreciated about hypercolor or the dye.
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Can you define the problem to me a little more clearly so that I 
can understand the question?  First off, what is a "Hypercolor T-shirt?"  My 
wife, who has a chemistry background, dyes fabrics as a hobby and is pretty 
familiar with dye chemistry.  She might be able to help; however, neither of 
us understand what you mean by "Hypercolor."
Topper
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"Hypercolor" T-shirts are a current clothing fad.  They are 
clothes that are dyed with a chemical that when touched by heat, turn a 
different color.  They can be found at most major department stores.  
Basically, you might have an orange T-shirt, and when touched with a warm 
hand, a purple hand print would be seen on the shirt.  This is "Hypercolor".
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Ah, I see. This is probably similar to the many toys on the 
market now which change color when submerged in hot or cold water, or to the 
drinking mugs which change color when hot or cold liquid is poured into them.  
Is this the general idea?  Well, unfortunately, although I have seen these 
toys and so forth, I must confess that I do not know exactly how they work. 
One guess is that there is some sort of chelated transition-metal complex, or 
some other compound, which can be readily (and reversibly) oxidized and 
reduced.  For example,under relatively mild conditions one can move Vanadium 
from the -1 up to the +5 oxidation state!  And there are color changes 
associated with each change in oxidation state....perhaps thermalized 
electrons are excited by warming the shirt, and these raise the color-changing 
compound to a higher-energy oxidation state, which relaxes over some long time 
scale as the system cools down....but this is all UTTER GUESSWORK!  What is 
needed is some worthy student to do some experiments and find out what is 
REALLY going on...also, you might consider writing a letter to the 
manufacturer of the t-shirt.  Good luck! I will write more later if I find out 
anything.
Topper
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Hyper color shirts are discussed in "chem matters" October 1992 
issue.  There are actually two dyes in hypercolor shirts.  A basal color dye 
that is always present, and another that is colorlesswhen cold and blue gray 
when warm.  Each hyper color capsule is 15 to 35 microns and contains several 
extractable dyes if you want more the articles explanation is extensive but 
written for high school chem students.
Gerald Bokowy
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