Acid Outgassing

Acid Outgassing

Overview

Acid outgassing refers to the natural release of acidic vapors from materials as they break down over time. In the framing and preservation world, this process poses a serious risk to artwork, photographs, and documents because the acids released can migrate into nearby materials, causing damage even if the artwork itself is not directly acidic.

How Acid Outgassing Occurs

• Material composition: Paper, cardboard, adhesives, and certain woods may contain acidic compounds that slowly release gases as they deteriorate.
• Environmental triggers: Heat, humidity, and light exposure accelerate chemical breakdown, increasing the rate of outgassing.
• Closed environments: In sealed frames, these gases may build up and cause concentrated damage to the artwork inside.

Effects on Artwork

• Discoloration: Prolonged exposure can lead to acid burn, yellowing, or brown staining of paper and mat board.
• Brittleness: Paper fibers weakened by acid exposure may become fragile and prone to tearing.
• Chemical transfer: Outgassed acids can migrate into non-acidic or acid-free materials, undermining preservation efforts.

Preventative Measures

• Use of archival materials: Choosing pH-neutral, lignin-free, and acid-free boards, mats, and adhesives reduces the risk of outgassing.
• Barrier layers: Acid migration can be slowed by using barrier tapes, films, or specialized mat boards that block gas transfer.
• Environmental control: Keeping artwork in stable, moderate conditions (low humidity, minimal UV exposure) slows deterioration and gas release.
• Ventilation and spacing: Framing methods that allow minimal air circulation can help disperse gases and reduce concentration buildup.

Framing Industry Context

Awareness of acid outgassing has significantly shaped modern framing practices. In the past, acidic mats, cardboard backings, and poor-quality adhesives were common, leading to irreversible damage. Today, framers prioritize archival-quality supplies and often use barrier techniques to protect against acid vapors. This shift ensures that frames not only look beautiful but also safeguard the integrity of the art within for generations.

Related Terms

• Acid Migration
• Acid Burn
• Ph
• Leeching