How Sand Casting Works: From Pattern to Finished Plaque

Many of the address plaques, skimmer lids and water scuppers we sell are sand cast to order by our foundry partner here in America. Sand casting is one of the oldest metalworking methods there is, and it's still the best way to make solid, heavy architectural pieces with crisp detail. Here's how it works, step by step.

1. The pattern

Every casting starts with a pattern: a full-size model of the finished piece. For a custom address plaque, the border and background are combined with your numbers and lettering to form the pattern for your plaque. Patterns are made slightly oversized, because metal shrinks a little as it cools.

2. The mold

The pattern is packed into a box called a flask, filled with specially bonded casting sand. The sand is rammed tight around the pattern so it captures every edge and letter. The flask is built in two halves, so the mold can be opened and the pattern lifted out, leaving a cavity in the sand the exact shape of the finished piece.

Channels called gates and risers are cut into the sand, giving molten metal a path into the cavity and a place for extra metal to go as it cools.

3. Melting and pouring

The metal is melted in a furnace. Aluminum melts at around 1,220°F, and brass at well over 1,600°F. Once it's at the right temperature, the molten metal is poured into the mold in one steady pour, filling the cavity before it starts to solidify.

4. Cooling and shakeout

The casting is left in the sand to cool and harden. Then the mold is broken apart, a step called shakeout, and the rough casting comes out with the gates and risers still attached. The sand is collected and reused.

5. Finishing by hand

This is where a casting becomes a finished piece. The gates and risers are cut off, the edges are ground smooth, and the surface is cleaned. Depending on the design, the piece is then:

• Polished to a high luster
• Given a contrasting background, so the raised numbers stand out
• Coated with a patina finish for a dark, aged look
• Drilled or fitted for mounting hardware

Why sand casting matters for your plaque

• It's solid metal. Unlike stamped or laser-cut signs made from thin sheet metal, a sand casting is solid all the way through. That's why our plaques and lids feel heavy in your hand.
• The lettering is part of the plaque. Your numbers are cast in, not glued or printed on, so they can't peel, crack or fade off.
• Every piece is a little unique. Sand leaves a subtle texture, and hand finishing adds small variations, so no two castings are exactly alike.
• It's built to last outdoors. Brass and aluminum don't rust, so a sand-cast plaque or lid can stay on your home for decades.

Why made to order takes a little time

Because each piece is molded, poured, cooled and finished by hand, our foundry partner casts most items to order rather than pulling them off a shelf. For water scuppers, plan on roughly two weeks before your order ships.

Wondering which metal to choose? Read our brass vs. aluminum guide, or browse our address plaques, skimmer lids and water features.