Catalogue Vs. Custom: 3 Things to remember about choosing ornamental plaster molding

St Thomas Aquinas College Chapel DrawingSimply stated, ornamental plaster molding is used to manipulate light and shadow. It can create depth and give the eye something to follow. Over time, molding and ornament has developed its own language . Traditionally, classical ornament was created to enrich the structure and meaning of the building. Sometimes they emphasize structural lines, and sometimes they’re used to hide them. Ornamental plaster molding can give scale, order, and definition to the space to emphasize nature and creativity, or strength and power. Ornamental designs have come to define the way in which our built environment is able to communicate. Over the years, as emphasis on traditional design and craftsmanship is slowing, and construction is streamlined, many turn to prefabricated designs made to emulate traditional styles.

Imagine using Google to translate a Shakespeare sonnet into Chinese, then reversing it back into English. If you carefully compare the important words, you may still be able to interpret the overall message, but the poetry of the language would be lost. The joining words and tenses may become skewed, and the results would be almost comically unpoetic. Architectural ornamentation is similar—without unifying the subtleties in the play between light and shadow, color and depth, symbolism and iconography under the same language—the message is diluted or skewed. Prefabricated ornamental molding may work in certain situations, but for the most part, it rarely fits the criteria needed to harmonize with the language.

Theory of Moldings Perspective

1. Perspective matters.

Objects further away appear smaller. This may be obvious, but what is less obvious is that this is one of the most important aspects involved in choosing the right ornamental plaster. Anamorphosis refers to the phenomenon where objects or images are skewed and stretched, but remain visually proportional from a specific point of view. The great masters of sculpture knew this, and took into account their viewer’s perspective when defining proportion. Sculptures placed in high, out of reach places, would have looked odd when placed on the ground—with heads way too big for their small torso, and even smaller legs. Their proportions were adjusted to correct for the viewer’s perspective. Leonardo Da Vinci first challenged the idea in 1485 when he created illusions that were unrecognizable straight on but were clearly visible from an extreme angle. Hans Holbein the Younger also played with the phenomenon in 1553. Ornamental architectural plaster molding is no different. Proportions must be adjusted for their placement. This means that the higher up the molding, the more it should lean inward toward the viewer, while moldings below the viewer should tilt upward. This creates an overall “face” of the molding, referred to as a facial angle. Just exactly how the scale of the molding elements are rendered depend completely on the nature of the building and can’t always be standardized.

2. Light is directional.

Theory of Architectural Moldings

In the same way that colors look different under different light, so does ornamental plaster molding. It is incredibly difficult to know how it will read when it is taken out of context. One of the purposes of molding is to manipulate light and shadow to create a three-dimensional surface that draws the eye into a visual path through the interior of a space. We’re naturally drawn to visual contrast, and the more definition ornamentation has, the more pronounced and eye catching it will be. Just as you would paint a swatch of color in place to see how it looks in the lighting, moldings should be chosen and studied for their placement—with the direction of lighting true to its final viewing point. That is why moldings should be interpreted by the effect of their shadows, not by the line of their profiles. They have a relationship with the specific direction and intensity of interior light.

acanthus leaf drawings

Variations of style depicting the acanthus leaf

3. Generational nuances in design can be subtle, but are still important for accuracy.

We often work on projects where the plaster ornament has been decayed over time and weathered by the elements. Re-instituting the decorative plaster ornament seems as simple as removing the damaged pieces and purchasing and installing the new. The subtleties of the original designs are always influenced by the time period in which it was created, and removing those influences completely is not possible. Without taking into account the historical influences, and unifying design elements, the shapes and structures begin to lose continuity. Take for example, the acanthus leaf, one of the most commonly used icons in art and architecture.

This image shows how differently the same subject can be rendered—due to the styles and cultural values of the time periods they were designed. Mixing one with the other causes distraction, and weakens the rhythm and language of the interior.


Sometimes you can find a piece of prefabricated ornamental molding that works, but when you take into account all these factors, it becomes difficult—almost impossible—to find a “perfect” match that won’t injure the harmony of the building. As caretakers of the buildings we’ve inherited from previous generations, it is our responsibility to act with sensitivity to the original designs, and more often than not, custom designed plaster ornamental molding is the only way these structures can be returned to their former splendor, and preserve the language with which they communicate.

Our Lady of the Most Holy Trinity

Our Lady of the Most Holy Trinity, Thomas Aquinas College Chapel. EverGreene designed, fabricated, and installed custom ornamental plaster molding.



1Blunck, A., and David O’Conor. Lessons on Form,. Second ed. Berlin: B. Hessling, G.m.b.h., 1905. Print.

2Walker, Charles Howard. Theory of Mouldings. New York: W.W. Norton, 2007. Print.