Cast Metal Plaques: Bronze, Aluminum, and Zinc Compared

Cast metal plaques are produced by pouring molten metal into a sand or precision mold. The lettering, logo, and any relief artwork are cast into the plaque at the same time as the background, which means they are permanent and will not wear off. The three most common metals for cast plaques are bronze, aluminum, and zinc. Each has its own characteristics, costs, and best uses. This page covers the practical details: the metals, the casting methods, the finishes, the common sizes, the mounting options, and how to choose the right metal for a specific project.

The three main metals for cast plaques

Cast bronze is the most traditional and prestigious metal for a cast plaque. The bronze alloy (typically a tin bronze or a leaded bronze) is poured into a sand or precision mold, finished, and either left natural (which patinas to a soft brown-green) or given a factory patina in a specific color. Cast bronze plaques are heavy, weather-resistant, and last 50-100+ years. They are the standard for cemetery markers, donor walls, dedication plaques, and architectural signage.

Cast aluminum is a lighter, more affordable alternative to cast bronze. The aluminum alloy is poured into a sand or precision mold, finished, and either polished, painted, or given a powder coat. Cast aluminum plaques are lighter and less expensive than cast bronze, but they are still weather-resistant. They last 30-50+ years. They are common for address signs, garden signs, decorative markers, and recognition pieces.

Cast zinc is the most affordable option. Zinc is a soft metal that is easy to cast in fine detail, and it is often used for plaques with detailed logos, monograms, or relief artwork. Cast zinc plaques are typically finished with a paint or a powder coat. They are less weather-resistant than cast bronze or cast aluminum, and they are usually used for indoor plaques or for outdoor plaques in moderate climates. Cast zinc plaques last 20-30 years with proper care.

Sand casting vs. precision casting

There are two main methods for casting metal plaques:

Sand casting is the traditional method. A pattern (a wood or metal replica of the plaque) is pressed into a sand mold to create a cavity. The molten metal is poured into the cavity, allowed to cool, and the plaque is removed and finished. Sand casting is well-suited to large plaques and to plaques with deep relief artwork. The surface is slightly grainy and the lettering is slightly softer than precision casting.

Precision casting (also called “lost wax casting” or “investment casting”) uses a wax pattern that is coated in a ceramic shell. The wax is melted out, the metal is poured into the shell, and the plaque is finished. Precision casting produces a sharper, more detailed plaque than sand casting, and it is the most common method for modern cast plaques.

For most projects, precision casting is the right choice. Sand casting is reserved for large architectural plaques and for plaques with deep relief.

Finishes and patinas

A cast metal plaque is usually given a factory finish in a specific color. The most common finishes are:

• Statuary bronze (deep dark brown). The most common patina for cast bronze plaques.
• Light statuary (lighter brown). A more subtle bronze patina.
• Verdigris (green). A chemical patina that gives the plaque an aged bronze look.
• Antique (mottled brown and black). A vintage look that is common for memorial plaques.
• Polished bronze. The bronze is left shiny and develops a natural patina over time.
• Black powder coat (cast aluminum). The most popular finish for cast aluminum plaques.
• Bronze powder coat (cast aluminum). A darker, more subdued finish.
• Painted zinc. A powder-coated or liquid-coated finish in a specific color. The patina is usually sealed with a clear coat to slow further oxidation. The sealer should be reapplied every 5-10 years in outdoor installations.

Standard sizes

Cast metal plaques are produced in a wide range of sizes:

• 4x6 inches (small address plaque, garden marker)
• 6x8 inches (small memorial, pet memorial)
• 8x10 inches (small bench plaque, recognition plaque)
• 9x12 inches (standard yard or garden plaque)
• 12x12 inches (larger plaque, dedication marker)
• 12x18 inches (large bench plaque, building marker)
• 18x24 inches (large architectural plaque, donor wall)
• 24x36 inches (large architectural sign, building plaque)

The thickness depends on the metal and the size: cast bronze and cast aluminum are typically 1/4 to 3/8 inch for a small plaque and 3/8 to 1/2 inch for a large architectural piece. Cast zinc is typically 1/8 to 1/4 inch.

Mounting options

The mounting method depends on the size, the metal, and the location.

• Concealed pins are the most common for cast metal plaques. Pins are set into the wall, stone base, or monument, and the plaque is bonded with a structural adhesive.
• Threaded rods are used for larger plaques. Rods are set into the wall and bonded with epoxy.
• Standoffs hold the plaque 1/2 to 2 inches off the wall. They create a contemporary shadow line.
• Flush mount sets the plaque into a routed recess in the wall or stone. The most secure and the most weather-resistant.
• Adhesive mount is used for small indoor plaques.
• Screw mount is used for larger door plates and small architectural plaques.

Weather resistance

A cast metal plaque is one of the most weather-resistant plaque materials.

• Cast bronze lasts 50-100+ years. The bronze alloy is weather-resistant and the patina is stable.
• Cast aluminum lasts 30-50+ years. The cast aluminum alloy is dense and non-porous, and the painted or powder-coated finish protects the surface.
• Cast zinc lasts 20-30 years. Zinc is more susceptible to corrosion in harsh environments, and the painted finish should be maintained.

To extend the life of the finish, the plaque can be washed once a year with mild soap and water. The sealer on a cast bronze plaque should be reapplied every 5-10 years.

Common applications

Cast metal plaques are used in many settings:

• Cemetery markers. Cast bronze is the standard for VA cemeteries and memorial parks.
• Garden memorials. Cast bronze or cast aluminum for memorial benches, garden stones, and tree dedications.
• Donor walls. Cast bronze or cast aluminum for building dedications and capital campaign recognition.
• Architectural signage. Cast bronze for high-end building dedications and historical markers.
• Office and home. Cast bronze or cast zinc for desk plates, door plates, and mailbox plates.
• Awards and recognition. Cast bronze or cast aluminum for employee recognition and service awards.

Cost ranges

The cost of a cast metal plaque depends on the size, the metal, the casting method, the finish, and the artwork. Approximate ranges for a mid-size plaque (8x10 to 12x18):

• Cast bronze: $400-$1,200
• Cast aluminum: $100-$400
• Cast zinc: $80-$250

Custom sizes, custom shapes, and complex artwork add to the cost. Cast bronze plaques with a sculpted bas-relief portrait are at the high end of the range.

Choosing the right metal

The choice between cast bronze, cast aluminum, and cast zinc depends on three factors:

• Budget. Cast bronze is the most expensive, cast aluminum is mid-range, and cast zinc is the most affordable.
• Prestige. Cast bronze is the most traditional and prestigious. Cast aluminum and cast zinc are more practical.
• Setting. Cast bronze is the standard for cemetery markers, donor walls, and architectural signage. Cast aluminum is the standard for address signs, garden signs, and decorative markers. Cast zinc is the standard for indoor plaques and for small, detailed artwork. For a cemetery marker, donor wall, or high-end architectural sign, cast bronze is the right choice. For a yard sign, garden memorial, or recognition piece, cast aluminum is the right choice. For an indoor plaque or a small decorative marker, cast zinc is the right choice.

Buying process

To order a custom cast metal plaque:

1. Choose the size, metal, finish, and patina.
2. Provide the text, dates, and any artwork in vector or high-resolution format.
3. Approve the digital proof or the sample.
4. Confirm the mounting method and the substrate.
5. Allow 3-6 weeks for cast aluminum and cast zinc, 4-8 weeks for cast bronze, plus shipping time if applicable.

Care and maintenance

A cast metal plaque is essentially maintenance-free. Once a year, rinse it with water to remove dirt and pollen. If the surface is stained, a soft brush with a mild detergent will usually remove the stain. Avoid harsh chemicals and abrasive cleaners. The sealer on a cast bronze plaque should be reapplied every 5-10 years in outdoor installations.

Frequently asked questions

References

• https://www.woodlandmanufacturing.com/cast-aluminum-plaque.html
• https://www.alphabetsigns.com/signs/aluminum-plaques.html
• https://www.impactsigns.com/plaques/aluminum/
• https://americancastbronzeplaques.com/cast-aluminum-plaques/
• https://www.laserengravedmemories.com/en/aluminum-plaques.html
• https://www.claruscrystal.com/collections/clean-and-simple-cast-metal-plaques
• https://signaturestreetscapes.com/blogs/blog/bronze-vs-aluminum-plaques
• https://www.plaquemaker.com/products/rectangle-cast-aluminum-signs
• https://hollandsupplyinc.com/product/cast-aluminum-signs/
• https://geminimade.com/signage/letters-logos/cast-metal/