Cast Crystal

How to make a crystal smooth?

I have a science project where I have to grow an alum crystal. I've got the growing part fine; i grew it to be about the size of two golfballs put together. The problem is, my teacher grades on the shape and smoothness of the crystal. My crystal is big, but there are tiny litle crystals growing on the outside so it makes it look really ugly and rigid. Any tips on how i could fix that without ruining the whole crystal? Thanksss.

Public Comments

1. If I remember correctly, you want slower growth.
2. Very fine sandpaper (500+ grit) and be very gentle. Your teacher is going to be able to tell that you altered it afterwards and it didn't actually grow smooth though.
3. Sounds as if you have secondary crystallization, and you may not be able to remove them. Try chipping them away with a needle. When growing crystals, placing a tiny seed crystal on the tip of a thread encourages the growth of a single crystal. Also as crystals form on the sides of the container or the top of the water, pour solution into a clean container and reseat the crystal in fresh solution.