The viscosity of a fluid is basically a measure of how sticky it is. Water has a fairly low viscosity; things like shampoo or syrup have higher viscosities. Viscosity also depends on temperature: engine oil, for instance, is much less viscous at high temperatures than it is in a cold engine in the middle of winter.
One small packet of 7 grams will produce about 500 grams of beads once they are hydrated. Soak overnight to a ratio of one packet of beads to 50 parts water. You can add more water or pour out any extra water when the beads expand. They can also be used to water potted/garden plants and flowers.
Sometimes the round seed beads are the right choice. Most of the glass beads we use for bead loom weaving (and they tend to have a catchall name of seed bead even when they are not round) come from either Japan or the Czech Republic. The Japanese beads tend to be relatively more consistent in shape and size and one has to cull fewer.