The process of preparing dinosaur bones excavated from the field is generally done in a laboratory, where a wide variety of tools and chemicals are available. The first step in preparation is to remove the rock from around the bones, using hand tools, dental picks, needles, microscopes, small pneumatic tools or anything else that does the job. This technique is laborious and exacting, and can only be mastered through hours of hands-on experience. Once the bones are exposed, they must be repaired, if needed, and stabilized to prevent further degradation. There are a wide variety of glues and adhesives that serve this purpose. Weak or cracked bones may require the addition of structural supports, such as fiberglass or steel bands.