by edneu3 » Thu Mar 15, 2012 11:42 am
I am not a chemist, and have worked with borax only as a cleaning agent, so I had to do a bit of research to answer your question.
Borax crystals are quite soft and colorless to slightly white. It seems the crystals your son grew are fairly typical. They are also fragile, which explains why they easily fall off the string.
There are many things that could affect the quantity of crystals that grew. This might also affect how well they attach themselves to the string. The things that could affect how well they grow include, the temperature of the water they were mixed in, the purity of the water, the concentration of the borax in solution with the water, how quickly the solution cooled to form the crystals, the rate of evaporation of the water in the solution as the crystals were growing, and probably several more.
For your son's science project, he should first state his hypothesis. That is what he expects to happen or observe. Then he should present what he did and what he observed, and how that compares to his hypothesis. This is the "scientific method".
I hope this helps, and that he has had fun!
Ed Neu
Buffalo, MN