Definition: Aluminum is a lightweight, soft metal known for its strength-to-weight ratio, corrosion resistance, and versatility. In the context of picture framing, aluminum is used both structurally-such as in extruded metal picture frame mouldings-and functionally, as a barrier material to protect artwork from environmental or chemical damage.

Overview

Aluminum is the most abundant metal in the Earth's crust and is commonly alloyed with small amounts of other metals to improve hardness and durability. In framing and conservation practices, it is valued for being lightweight, non-rusting, and chemically stable when properly coated or anodized. Its role ranges from serving as a visible frame moulding to being hidden as a structural or protective layer within framing assemblies.

Applications in Picture Framing

Metal Frames: Extruded aluminum mouldings are a popular choice for modern and minimalist framing, offering strength with a narrow profile.
Rigid Sheet Goods: Aluminum composite panels (e.g., Dibond) combine aluminum skins with a polyethylene core, used for mounting large-scale works.
Foil Barriers: Thin aluminum foils may be used as an interleaving layer to block acid migration from non-archival backboards into artworks or mats.
Substrates for Printing: Used as the base for aluminized prints and fine art reproductions directly bonded to metal.

Conservation and Archival Considerations

Raw aluminum can corrode and may outgas over time if left untreated. In conservation framing, aluminum is typically anodized or sealed to prevent reactions with surrounding materials. When used as a foil barrier, it must be laminated or buffered on both sides to avoid potential metallic transfer to delicate works. Direct contact with highly alkaline adhesives or paper should be avoided without proper interleaving.

Comparison with Other Materials

Aluminum vs. Wood Moulding: Wood mouldings offer warmth and traditional craftsmanship, while aluminum mouldings provide sleek modernity and dimensional stability.
Aluminum vs. Steel: Aluminum is lighter, non-rusting, and easier to cut, whereas steel offers greater tensile strength but is prone to corrosion without coatings.
Aluminum vs. Plastic Composites: Plastic mouldings may be cheaper and lighter, but aluminum provides greater longevity and stability.

Common Misconceptions

"Aluminum is archival by default." While corrosion resistant, untreated aluminum is not inherently archival and should be sealed, anodized, or isolated in conservation-grade framing.
"All aluminum frames look industrial." Modern aluminum mouldings come in a wide range of finishes and colors, from brushed metal to woodgrain coatings, expanding their aesthetic use.

Aluminum