Holiday Crafts: Crystal Christmas Trees
It’s the most wonderful time of the year! As parents and teachers, we know the awe and wonder at the crystal growing process never wains. Each crystal develops so uniquely that different crystal growing experiments are enjoyable to watch. Using engineering to build crystal Christmas trees and chemistry to mix this reactionary solution, your kids will get a huge kick out of watching these holiday-themed crystals grow!
- Food coloring/watercolor paint
- Table Salt
- Ammonia (optional, but speeds up the process)
- Mrs. Stewart’s Bluing
- Dish (large enough to hold your tree with room for crystals to grow)
Trace and cut out the trees. I used a straight edge and made a few small trees. Once cut out, I put two together to match cutting branches. Once that was done, I cut two notches – one on top of one tree, one on the bottom of the other so that they could slide together.
Next, we painted our trees. We used watercolor paint and painted them red and green for the holiday.
I used a tad bit of hot glue to be sure they would stick together okay.
We made our crystal making solution next. We used 4 Tablespoons of warm water, 4 Tablespoons table salt, 4 Tablespoons Mrs. Stewart’s Bluing, 2 Tablespoons ammonia. Place in bottom of dish.
Stand trees in solution. Crystals should begin to grow within a few hours. By the next day, behold a grand tree!
The structures are extremely delicate so if you want to preserve the tree, make sure you don’t bump it or the crystals will fall right off. If you want the tree to grow more, just add more solution.
It was neat to see our crystals take in the color of paint we used on the tree! It looked like it had “snowed”.
The solution we mixed up created a suspension, a mixture that has solid particles that are large enough for sedimentation (settling out). Our solid particles settled out on the cardboard tree due to a couple of processes.
First, the liquid suspension is drawn up the cardboard tree through a process called capillary action. This is the ability of a liquid to defy gravity and flow upwards.
In narrow areas, the combination of surface tension of water and the adhesive forces between the container and the liquid help to lift the liquid. This effect can be seen when a plant like celery draws up colored water through its capillaries, when paint is drawn up between the bristles of a paintbrush, and when porous materials like cardboard draw up water.
The next process is evaporation, where liquid molecules escape from the solution as gas molecules.
Ammonia evaporates much quicker than water and we added it to the solution to speed up the evaporation process. Once the solution traveled up the cardboard and evaporated, the next process could occur.
The final process, crystallization, occurred as the water and ammonia molecules leave the solution through evaporation. The bluing and salt that remain can no longer be supported in the remaining solution and begin to crystallize.
Mrs. Stewart’s Bluing is a colloidal suspension of extremely minute particles of blue powder (Ferric Hexacyanoferrate). These minute particles act as nuclei, or seeds for crystallization to take place. This is similar to the process that occurs in cloud formation.
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Photos & content by: Heather Kucenski