Crystallization projects are never as easy to do as they look. Here are some suggestions that may help:
1. Did you make a supersaturated solution the first time or two? This means heating the sodium acetate until the water would not hold any more solid, and then decanting the liquid away from the solid crystals? Your description of the trial with liquid on the bottom suggests that you really didn’t have a supersaturated solution.
2. Did the sodium acetate solution sit undisturbed until you initiated the crystallization with a seed crystal of sodium acetate?
3. Your latest description sounds like you do have a supersaturated solution, but there may be small particles in the sodium acetate solution that are acting as a nucleus for the crystallization. If you have more than one point where the crystallization starts, you won’t get the glass effect. You would need to heat the solution and use a coffee filter or other fine filter to try and remove the particles (they may be microscopic) that are causing the premature crystallization. http://www.chemistry.co.nz/crystals_forming.htm
4. If there were any contaminants in the sodium acetate, this could have caused interference with the formation of the crystal structure. What was the purity of the sodium acetate? Could any fat or oil (fingerprints) have been in the sample? This would interfere with crystallization.
You have tried multiple times, and the experiment is not working as you expect, however, this is a complete project, so you should write it up and present the results. A project that includes all sections of a science project is as acceptable as one that has perfect results:http://sciencebuddies.org/science-fair- ... oard.shtml
Be sure to include an explanation of crystallization in the background information, and an explanation of why you didn’t get the glass effect for the results. You should also include what you would do differently next time, if you had time to do another experiment.