Re: My daughter and I made homemade popsicles using a plastic stick that you

A very perplexing question! And where I live, it's too cold to make popsicles in December!!

So, what could have happened here? As I understand it, you made Kool Aid popsicles and when you took them out of the container and exposed them to the sun, the colour disappeared. But prior to exposing the popsicle to the sun, was the colour evenly dispersed in the popsicle? I am assuming that this is the case and not that the colour was simple on the "outside" of the popsicle so that when the surface melted, it all dripped off.

This is a possibility when trying to freeze coloured water or juices, because as the ice freezes, the lattice will tend to force other substances to be exuded. But generally, if this happens, because freezing occurs from the outside in, the colour or contaminants are trapped in the centre of the ice and not on the surface. This is why whenever I have made Kool Aid popsicles, I have always found that the centre is the darkest in colour and most concentrated in flavour. It is possible to freeze ice from the inside out (which would trap the colour and such on the surface), but with the apparatus that you have described it is not likely. Certainly, whenever I have made Kool Aid popsicles using the plastic trays, I have never observed this to be the case.

So, if I am right in presuming that the colour (and flavour) were uniformly dispersed throughout the popsicle, then what must have occured is something called "photobleaching". That is, the sunlight striking the popsicle must have caused the colouring agent to undergo a photochemical reaction that destroyed the colour centres. This is a fairly common reaction in nature as all sorts of compounds are susceptible to photolysis. Some produce colour (i.e. the tanning molecules in our skins) while others just fade away (i.e. the colour in flag that is left out for long periods of time). Most typically, coloured compounds will photolyze to give colourless species. This is why paints fade and plastics look paler with time.

However, having said that, I have never observed the colouring agents in Kool Aid to be susceptible to photobleaching on the sort of time scale that would allow you to be left with just the ice. Without knowing the flavour that you were using (and exactly what occured), it is a bit hard to say much than that. If it was just the colour on the outside melting away, then you have just managed to freeze the popsicles from the inside out. If the colour truly disappeared, that would be unusual but would be an example of photolysis.

Hope this helps - although with out knowing more it is hard to answer this question!