Manufacturing – The Process

The process we use for manufacturing our products is called rotational molding, or roto-molding. Roto-molding makes a uniform product line using extreme precision and yielding great durability of rims, edges and corners.

Roto-molding starts with a metal mold. Each mold is made of two mirror image halves that fit together and form a hollow center in the exact shape of the product being cast.

Material

Whether it is new or recycled resin, it starts in pellet form as little bits of Linear Low Density Polyethylene. Recycled resin comes from petroleum manufacturers, like Exxon Mobil or Dow Chemicals. The resin pellets go into the pulverizer and are made into a fine powder. This powder is the base for all of our resin products.

Depending on the color choice, we can use up to 100% post-consumer recycled material. With our darkest colors being 100% recycled, black is the new green at TerraCast®. We also use sustainable practices in our factories. Our ovens are heated with natural gas and our cooling chambers use reclaimed water. We’re so green; we qualify for LEED credits.

Coloring

The powder base is put into the color blend machine. We offer all kinds of solid colors from simple black or white to our proprietary Tennessee Green. We then blend a UV inhibitor right into the resin, to make sure your color stays true for years to come.

We have six proprietary stone blends including Brazilian Terracotta, Ash Granite, Sandstone Granite, and Verde Granite. For those, we use a combination of colors mixed together into a translucent base blend. The Verde Granite blend, for example, is a green translucent with speculate added in different shades of green, black and white.

We can match or create any color you desire and even create your own unique granite blend as well.

Cooking

Once the color is blended, the blended resin powder is measured out and poured into a clamshell mold. The mold is closed, locked and placed in a special oven to “cook.” These ovens heat up to 500 – 650 degrees depending on the size, shape, and prescribed cook time of the item.

While it’s cooking, machine arms rotate the mold on a bi-axle rotation giving it 360 degrees of movement. This motion ensures that no corner or detail goes unfilled and every inch of the mold is evenly coated.

The resin melts, liquefies and cakes into the mold, building the product from the outside in to ensure there are no areas uncovered or other defects.

When the cook time is up, the mold comes out of the oven into a cooling chamber where it is rinsed with reclaimed water for 15 minutes to cool slowly and evenly. After which, it comes to a workstation where a special tool is used to pry the casting out of its mold.

This combination of material and manufacturing methods make our products virtually indestructible.

Maintaining

What are not indestructible are the molds themselves. The molds are made of metal and are susceptible to rusting, pitting, corrosion and other damaging conditions.

Our molds are maintained regularly; each inspected, repaired, refinished and prepped for production.

We take great care in the storage and maintenance of our molds. Most molds can make 7,000-8,000 castings before they need serious attention.

Some of the original molds made in the 1970s by our founder, Bob Grossman, are still in production today, thanks to the meticulous care and maintenance they receive.