Acid free refers to materials that are either neutral (pH 7) or alkaline (pH above 7) on the pH scale. In the picture framing and conservation industries, this term is critical because materials containing acid can cause long-term deterioration of artwork, photographs, and documents. Acid free products are designed to prevent chemical damage, ensuring that framed pieces remain stable and intact over time.

Why Acid Free Matters

Preservation: Acid free materials protect artwork from discoloration, brittleness, and staining caused by acidic reactions.
Longevity: Essential for archival framing, acid free products ensure that valuable or sentimental items remain in excellent condition for decades or centuries.
Professional standard: Museums, galleries, and conservationists require acid free materials to meet archival standards.

Common Acid Free Materials in Framing

Mat board: High-quality mat boards are often acid free to prevent acid migration into artwork.
Backing boards: Acid free backing boards provide safe structural support for framed works.
Tapes and adhesives: Conservation-grade, acid free adhesives are used for hinging and mounting artwork.
Storage products: Acid free boxes, sleeves, and papers protect documents and photographs in archival storage.

Acid Free vs. Archival

While the terms "acid free" and archival are often used interchangeably, they are not identical. Acid free specifically refers to the pH level of a material. Archival materials, on the other hand, go beyond pH balance by also meeting strict standards for purity, durability, and resistance to aging factors such as acid migration and oxidation. An acid free material may not necessarily be archival unless it meets these higher conservation standards.

Risks of Non-Acid Free Materials

Acid Burn: Brownish stains or halo effects, often irreversible, caused by acidic deterioration.
Embrittlement: Paper and textiles may become weak and prone to tearing.
Color change: Artwork can yellow or darken due to acidic chemical reactions.

Framing Industry Context

Since the mid-20th century, acid free products have become a cornerstone of professional framing practice. Early frames often used acidic wood pulp boards that led to widespread damage, motivating the development of pH-balanced materials. Today, acid free matting, backing, and adhesives are considered industry best practices, especially when framing valuable, historical, or sentimental works.

Acid Free