The Basics of Cast Concrete and Molded Accents

Learn more on the history of cast stone and the process of making and using molds to create architectural accents from Restoration Realities .

Related To:

  1. Concrete
basics of cast concrete and molded accents

basics of cast concrete and molded accents

Casting the Stone

Cast concrete or "cast stone," as it is properly called, has been in use literally for centuries. Ancient Romans and Etruscans used lime and other minerals to make concrete that was then formed or cast into various shapes, including decorative sculptures for buildings. Even the ancient Egyptians used a similar process to cast some of their sculptures. The quality of any cast concrete depends on the mix of minerals. Traditionally, lime was the major ingredient. However, even the Romans created both low quality concrete using only lime and higher quality concrete -- which added more expensive minerals. Today, Portland cement is the modern choice and cast concrete is utilized on many buildings as a lower-cost alternative to natural solid stone.

Also important to the quality of most concrete mixes is the amount of water utilized. A soupy mix will yield a casting that is soft and vulnerable to wear and damage. A somewhat dryer mix will yield a more solid stone-like quality concrete.

Another important factor in achieving a quality concrete casting is to make sure all of the air pockets are eliminated as the mold is filled with wet concrete. To do that the concrete should be added slowly and shaken down or tamped into the mold.

Making the Mold

Mold-making is another centuries-old tradition. Molds can be complex like those made to cast automotive parts or as simple as the plastic molds that children use to cast clay toys. There are many compounds used to create molds. The two most common are plaster and silicon RTV (room temperature vulcanizing) rubber. While the mold-making process can sometimes be complex and involve many steps, the basic concept is not a mystery. You can learn to do it yourself. The basic elements needed to make any mold are:

  • A model -- from which the replicas will be cast.
  • A mold medium -- plaster is common, as is silicon RTV.
  • A sealing medium like shellac -- so the model won't get stuck in the mold.
  • A parting agent or mold soap -- so the casting won't stick to the mold.
  • A cleaning solution -- to clean up the mold after each casting.

Next Up

Tips for Demolishing Concrete

Learn how to break up an existing concrete pad without becoming overwhelmed or injured.

What’s the Best Type of Concrete Deck Blocks?

If you’re building a new deck, make sure you start off on the right foot with the best concrete footers.

Composite Wood Basics

Host Paul Ryan explains the benefits of buying and using composite wood.

TIG Welder Basics

The Tungsten Inert Gas (TIG) welder generates heat from an electric arc between the electrode at the tip of the torch, the filler rod, and the metal part that's being welded.

Band-Saw Basics

When making carefully crafted parts for furniture or cutting the same design into several pieces of wood at once, the band saw is the tool of choice -- and one of the most versatile tools available.

How to Clean a Cement Patio

Get your cement patio ready for outdoor entertaining with these cleaning tips from DIY experts.

All About Concrete, Mortar and Aggregate Material

Learn about the different types of concrete, mortar and aggregates and how to choose the right materials for your project.

How to Clean Concrete Floors

Cleaning outdoor concrete flooring is very different from indoor concrete flooring. Here's how to remove dirt and mildew without damaging your concrete floors.

Carpet Basics: Durability and Judging Quality

Here are some general terms for understanding how carpet is made and how to judge carpet quality.

Concrete Basics

A durable and economic material, concrete can be used for a number of projects. Randy Williams of Quikrete offers a lesson in the basics of making and using concrete.

Stories We're Following

Get Social With Us

We love to DIY. You love to DIY. Let's get together.

Discover Made + Remade

See the latest DIY projects, catch up on trends and meet more cool people who love to create.

Make It. Fix It. Learn It. Find It.