You probably have us figured out... that Magic Crystal Tree isn't magic at all! You're right, but do you know the science behind the crystalline growth of the cardboard tree?
The main principles at work here are capillary action, evaporation, crystaliztion, and saturation.
Capillary action is the same process that enables plants and trees to take water and nutrients from the soil up through their stems or trunks and into their leaves, branches, flowers, and fruit. The cardboard tree uses the same process to draw the magic solution up through its entire shape until the cardboard has soaked itself in the solution.
After the magic solution has been drawn throughout the tree by capillary action, the solution begins to evaporate. The evaporation process is accelerated by the ammonia, which evaporates more quickly than water. As the magic solution evaporates off of the tree, the crystals are left behind on the branches of the tree.
The magic crystals that are left behind are a combination of the Mrs. Stewart's Bluing and the table salt. The solution that you create is a supersaturated by the bluing and salt that you add to the water. The bluing is a colloid, with many tiny particles suspending themselves within the water. It's just like when you shake up a snow globe, except the particles of bluing are much smaller than the snow. As the bluing and salt water make their way up the tree, the water begins evaporating. These means there is less water able to support the bluing particles and dissolved salt. This evaporation allows the salt and bluing particles to crystallize, resulting in your