How does a crystal garden grow?
I bought my little girl a crystal garden for her birthday. It involved growing a multi-colored winter scene out of crystal on a barren paper background. She had so much fun watching it grow over the last few hours. However, when she inquired as to how it worked, I took to the internet, since the kit did not have the information,and have not been able to find out how the crystals grew on the paper in multiple colors from pouring clear "magic water" in the grooves of the tray the paper objects could absorb it from. I myself am curious, and would really like to be able to explain it to my daughter. Can anybody help explain this to me?
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Verified answer
These scenes are usually prepared by using silicates. Sodium silicate solution, also known as waterglass, is the usual method of choice. Sodium silicate is soluble, but pretty much all other silicates are not. My guess is that the grooves in the tray contained different chemicals with varying colours, which deposited as silicate crystals onto the paper. That, or else the paper contained these substances, which formed crystals as the solution was absorbed. Copper would give green or blue crystals, manganese would give pink, and magnesium would give white. There are many other coloured compounds that work here.
Another point is that the "skin" of the growing crystals is porous to water. Water will slowly enter the crystals through osmosis. This will stretch the outer crystal film, until it splits. This will deposit a new layer of silicate, sealing the split, and the cycle starts again, making the crystal grow more, until the original chemical is used up and the crystals stop growing.