Sources &
editorial policy.

How the guides are checked

Guides are reviewed for practical clarity, cautious recommendations and a clear line between observation and diagnosis. Technical and preservation claims are checked against the authoritative collections listed below when they apply.

Old and valuable work needs restraint

Historic or valuable pieces should be inspected before aggressive cleaning, stripping or repair. Older painted wood can contain lead. Follow product labels, use suitable ventilation and protective equipment, and arrange appropriate testing when the paint history is uncertain.

Authoritative collections

• USDA Forest Products Laboratory Wood Handbook
• National Park Service Preservation Briefs

Advice changes with the material and condition in front of you. When those details cannot be established from a description or photograph, the responsible next step is an inspection—not a stronger product.