As promised in a previous posting I have checked into the mystery of the Colourful Candles and, I think, I have more or less solved most of the magic behind their colour changing behaviour.
Following is a picture of the candle just taken out of the box it comes in.
Sorry about the grainy-ness of the picture but I took this shot in a pergola in overcast conditions so I had to wind the ISO up to 1600 to avoid using the flash and to eliminate camera shake.
As you can see, at this point—ignoring the writing on the box it came in—it looks like a fairly normal candle.
At left there is really good candle close-up. Well I thought it was really good candle close-up anyway. About as good as a boring candle close-up taken in overcast conditions without using a flash can probably be. No doubt it could have been massively improved could I have engaged either Jennifer Hawkins or Lara Bingle to model it for me somehow, but failing that, not too bad of an effort for a candle close-up.
The point of this close-up is that there is no hint of what this candle is going to do once it is booted up, errr, lit—assuming you have not seen the box it came in; as I had not when I first saw one of these candles operating (errr, alight).
I would also note at this point that my guess at the candle's size in my original post was close. It is, as I guessed, exactly 4" tall; but my guess at the diameter of 2" was 1" out. It has a 3" diameter. For those Australians who came along a bit later than me and have no idea what a (") is, 4" is about 10.5 cm and 3" is about 7.5 cm.
In the next two pictures we see SCN (seriously cute niece) about to light the candle, and then the expression on her face when the candle starts to change colours.
To see some pictures of the candles lit at night and the colours they emit then go to the original post here.
So—how is it done?
Well it seems that there is one or more tiny colour changing LEDs in the bottom of the candle powered by a miniature Lithium battery—at least this is what the packaging infers. They must be tiny because they cannot be seen through the candle wax.
Then there is some kind of optic fibre embedded within the candle wick. Igniting the wick causes the switch on the battery to connect and the LED (or LEDs) to start doing the colour changing trick. When the wick is extinguished the battery disconnects.
All for $9.99
According to the instructions on the box the candle lasts for 20 hours. So for $9.99 (Aus), which is what one candle costs, I would say you are probably getting reasonable value for money.
To top it off a burning candle will keep mosquitoes away—for those that believe mosquitoes don't like citronella.
P.S. For anyone interested, these candles were purchased from Bunnings Hardware in Western Australia. I have no idea where you get them in the USA.