This instructable if my contribution to the Instructable Advent Calendar 2011
While making my ornament it occurred to me that this project demonstrates some simple principles of solution chemistry so I included a learning objective and a discussion of the science behind it so I can enter it into the Teacher Contest.
Step 1: What you will need:
- Clear glass ornament -you can get these at craft stores (or any other glass object you want to decorate)
- Sharpies or other permanent markers
- Rubbing alcohol (use in a well ventilated area and away from open flame)
- A dropper/pipette and a small spray bottle
- Newspaper or drop cloth to protect your work surface
- (Optional) disposable gloves
Step 2: The Science
Permanent markers are designed to be waterproof, which means that the ink (solute) does not dissolve in water. However it does dissolve in alcohol. The solubility of the solute in a solvent is generally due to polarity. If the polarity of the solute and solvent is the same then it will likely be soluble, so in this case the ink has the same polarity as alcohol but not water (compare image 3 and 6 above).
When you drop or spray alcohol on ink drawn onto the glass surface the ink dissolves into the alcohol forming a solution (see image 3 above). The solution spreads out over the surface of the glass (see image 4). As the alcohol evaporates the concentration of solute increases and the ink begins to precipitate depositing the ink onto the glass creating interesting patterns of colour (see image 5 above).