Acid-Free
Acid-free materials are pH-neutral, meaning they won't yellow or become brittle over time from internal chemical breakdown.
Acid-free refers to paper, mat boards, and mounting materials that have a neutral or slightly alkaline pH (7.0 or higher). Ordinary wood-pulp paper contains lignin and residual acids from the manufacturing process, which cause it to yellow and turn brittle over decades — the reason old paperback books feel fragile and look browned.
For framed artwork, every material that touches the print should be acid-free: the mat, the backing board, the hinges or photo corners, and any tape. A single non-archival component can migrate acid into the print and damage it permanently.
Look for the terms "acid-free," "archival," "buffered," or "conservation-grade" when specifying framing. Reputable custom framers use these materials by default; budget framing often does not.
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