About 8 cells are required to establish a temperature and relative humidity curve for the site. With this background work done, the environmental conditions can be determined for any context at a site. The Limitations of Obsidian Hydration Dating Using this technique, any sample of obsidian can be dated. There are several limitations, however. The rate of hydration is not uniform throughout the world.
Variations exist in temperature over time from site to site.
Temperature effects are particularly difficult to evaluate. Variations also exist in sample chemical composition. Samples from different obsidian sources hydrate at different rates. Moisture is another source of variability. The amount of moisture present at a site can affect the hydration rate of an obsidian sample.