How to grow your own crystal precipitate tree

What’s needed:

• 90 ml water
• 6 tablespoons table salt (preferably uniodized)
• 90 ml Mrs. Stewart’s liquid laundry bluing [manufacturer’s website] (Chemically known as ferric hexacyanoferrate, Fe4[Fe(CN)6]3 - Despite containing cyanide groups - they are so tightly bound to the iron that they pose little threat if ingested -it’s often used as a treatment for ingestion of radioactive elements Thallium and Cesium)
• 15 ml household ammonia
• Felt tip markers
• Absorbent cardboard cut into the shape of a tree

Decorate the carboard tree with markers if desired. Dissolve all ingredients then place cardboard tree above so it’s just touching the solution. Alternatively dab the bluing on the tips of the carboard where you want crystals to form instead of adding it directly to the solution.

What happens:

As the water from the bluing and the clear water which is added evaporate, two things happen. The blue particles can no longer be supported and the excess salt cannot stay in solution. The salt crystallization process will take place around the blue particles as nuclei. Small amounts of ammonia are added to speed up the evaporation process. Ammonia evaporates very quickly and aids the other liquids to do the same. No chemical reaction occurs - this simply demonstrates the crystallization process.

Sources: 1. 2.
GIF video source