molded and cast ornament

Moldings & Cast Interior Ornament

Manufacturers of polymer moldings are paying more attention to historical accuracy -- causing these easy-to-use elements to be specified more frequently in traditional designs, along with the usual materials.

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Anyone who has struggled to get an interior wood molding to wrap cleanly around a curved surface will become positively misty eyed over flexible polymer moldings. And lightweight polymer ceiling medallions and cornices install easily with ordinary carpenter's tools and closely mimic plaster ornament when painted. So it's small wonder that polymer millwork has been gaining in popularity. Even so, there are many applications where traditional wood and plaster moldings are still the best choice. Here's an overview of current usage.

WOOD MOLDINGS.When clear finishes are being specified for interior surfaces, hardwood moldings are almost an automatic choice. Also, when custom elements are needed, wood's ease of carving and shaping often make it the most economical material for short-run custom work. Computer-driven production machinery has also reduced the cost of making stock patterns of hardwood moldings.

BASIC PLASTER. Traditional plaster moldings have two big advantages. First, they provide clean, crisp edges at an economical price. Second, the material is inherently fire resistant and carries a Class A fire rating without special additives or coatings.

The downside of traditional plaster is that it is heavy, porous and fragile, qualities that make it relatively expensive to ship and install.

GYPSUM AND MODIFIED GYPSUM. A modern cousin of cast plaster ornament is GRG -- glass-fiber reinforced gypsum, sometimes called GFRG. Moldings of GRG are lighter in weight than plaster and have more impact resistance.

It's also possible to modify gypsum with a polymer like Forton, adding even more impact resistance as a result. When combined with high-strength glass fibers, the very dense modified-gypsum moldings outperform fiberglass-reinformed plastic (FRP) and GRG in dimensional stability. This is especially important in large, complex assemblies, where pieces have to fit together snugly. The high impact resistance of polymer-modified gypsum elements also makes them desirable for high-traffic areas, where the molding may be subjected to abrasion and bumping from passersby. Modified gypsum moldings can also be made with a wide range of cast-in faux finishes, such as making an economical gypsum element look like cast bronze. Modified gypsum also carries a Class A fire rating, making it a desirable material for many commercial projects.

FOAMED URETHANE. Foamed urethane moldings are strong -- and lighter and easier to install than plaster. (Urethane moldings are roughly one-sixth the weight of plaster.) Most urethane pieces come already primed, so installation is even faster. In some cases, foamed urethane doesn't have quite the crispness of traditional plaster moldings, but once painted, most urethane moldings cannot be differentiated from plaster elements.

FLEXIBLE MOLDINGS. Solid polyester resins can be used to make flexible moldings. Though relatively expensive compared to wood and foamed urethane, these specialty flexible moldings can be a life-saver when you're dealing with irregular surfaces.

FIBERGLASS. Fiberglass-reinforced plastic (FRP) is more often used for exterior elements but has applications for large interior moldings such as ceiling panels for interior corridors. FRP moldings are lightweight and easy to install. Though regular FRP is flammable, it can be formulated with additives that yield a Class 1 flame-spread-resistant material.

RELATIVE COSTS. There are no hard-and-fast rules regarding relative costs because each job is different. Often, a specification is driven by which supplier has the desired profile, regardless of material. Some very general rules of thumb are: (a) A pre-cast plaster molding is roughly 40% of the cost of a run-in-place molding; (b) Ornamental plaster is as much as 80% less than a highly ornamental hand-carved wood molding; (c) the installed cost of foamed urethane moldings is less than that of plaster moldings and (d) polymer-modified gypsum moldings are roughly 10% more than plaster. But when custom work is involved, the previous guidelines go out the window because much of the cost is consumed in the first-phase model making.

Click here for companies doing custom casting
Click here for suppliers of ceiling domes
Click here for suppliers of ceiling medallions
Click here for suppliers of cornice moldings
Click here for suppliers of niches
Click here for suppliers of ornamental moldings