Enzymes are biological catalysts that can be used in conservation to break down specific substances without harming the underlying material. In document conservation, enzymes are particularly useful for carefully separating sheets of paper that have become stuck together due to adhesives, water damage, or mold growth. The enzymes break down the adhesive or the degraded paper material holding the sheets together. Enzymes are not typically used for brittle documents (which require support and strengthening), insect-infested documents (which need pest control first), or faded documents (which might require other treatments like ink consolidation).