acid-free
UK[ˌæsɪd ˈfriː]US[ˌæsɪd ˈfriː]
adj
Not containing acid; having a neutral or alkaline pH, especially used to describe materials that will not damage other materials over time.
adj
Specifically, (of paper or storage materials) treated or manufactured to lack acidic compounds, preventing deterioration and preserving documents or photographs.
Morpheme Breakdown
acid
free
acid
chemical substance
free
without
Etymology
The term is a modern English compound adjective formed by combining the noun 'acid', derived from the Latin acidus meaning "sour" or "sharp," with the adjective 'free', from Old English, meaning "exempt from." The logic is transparently descriptive: "free from acid." It emerged in the 20th century, primarily within industrial chemistry, conservation science, and archival fields, to designate materials processed to remove or neutralize acidic components. This specification was driven by the need to prevent the chemical degradation caused by acids in products like paper, adhesives, and storage boxes, thereby extending the lifespan of valuable documents and artifacts.
Analysis
Structure: acid (chemical substance) + free (without)
- acid: From Latin acidus (sour, sharp). In this compound, it functions as a noun denoting a class of chemical substances.
- free: From Old English frēo (exempt from, not in bondage). In this compound, it functions as an adjective-forming suffix meaning "without" or "lacking."
Examples
For long-term preservation, always use acid-free paper for important documents.
The museum stores its photographic collection in special acid-free boxes.
This adhesive is labeled acid-free, making it safe for scrapbooking.