Iron Age Designs Finishes & Coatings
In general, all the grating that is discussed on this website is assumed to be made from raw, uncoated, cast iron. These grates will begin to rust soon after exposure to humidity. Don’t worry, though, the oxidation will stop and your grate will have an attractive protective patina that is the color of light chocolate. There are options other than raw iron. These are discussed below.
Alloy Options
Cast Iron is not the only cast metal selection you have. However, cast iron is usually the most economical. Other metals available include:
- Cast Aluminum
- Manganese Bronze
- Brass
- Ductile Iron
For pricing on any of Iron Age’s current patterns with a custom alloy, please contact your Trenchdrain.biz representative.
Finish Options
One of the most popular and economical finishes for a raw cast iron grate is Iron Age’s baked on oil finish (BooF). This process involves baking a cast iron grate at 160oF for two weeks after soaking it in vegetable oil. The result is a casting that has a shiny brown appearance.
The purpose of the baked on oil finish is to accelerate the natural oxidation process to achieve a stabile oxide patina. This oxide coating is the stabile mineral hematite (Fe2O3) and protects oxygen from reaching the raw iron phase just below the surface. Think of the manhole covers and inlet grating you see in the highways and streets in your neighborhood. They may have been there for years and have a deep brown color. That is the effect we are achieving with the BooF.
Powder Coatings
Iron Age offers a powder coating service for their grates. Powder coating is a dry paint powder that is applied to the casting electro-statically. After the appropriate thickness of powder has coated the surface, the casting is heated in a large drying oven. The temperature of the oven reaches the melting point of the paint powder. This heat treatment forces the liquefied paint into the pours of the casting and simultaneously drives off the volatiles which allowed the powder to become fluid. In essence, the powder coating becomes liquid then solidifies on the casting.
Paint Coatings
Iron Age and Trenchdrain.biz both offer painting services for gratings. Iron Age has a number of standard paint colors available. Trenchdrain.biz is able to provide custom colors. We recommend an epoxy primer coating for water resistance followed by a polyurethane finishing coating with UV inhibitors.
Iron Age does not recommend coating drain grates and tree grates that will knowingly be walked or driven over. Powder coating, especially, will have a tendency to chip off under these conditions, leaving raw metal exposed to the elements.
