STRETCHERS

A Key Advance

By roughly the middle of the 18th century, it was clear that the fixed joinery of the earliest stretcher designs represented a serious limitation. To compensate, keying was invented to allow for expandable joints. 

Keying can take various forms, but its functional role is to endow a stretcher with built-in maintenance potential that allows for adjusting the canvas tension in small increments. 

Otherwise, a fixed frame known as a strainer all but ensures that the artwork will have to be re-stretched and reframed at some point.

The earliest keyed stretcher designs were less than perfect, but the craft and components of keying gradually became more sophisticated and secure.

Simon Liu’s personal keying designs and innovations have all stemmed from the principle that there is always room for improvement, even within traditional canvas stretcher forms.

Abundant But Not Necessarily Better

In the early, pre-industrial days when every stretcher was slowly built by hand, it’s fair to say that accuracy and precision suffered even when the craftsmanship was exceptional. Eventually, that problem reversed.

With the 19th century came the advent of commercially produced canvas stretchers. Critical design improvements resulted, but individual craftsmanship went into decline. Machines could churn out relatively consistent, inexpensive canvas stretchers in great numbers, but the diminished integrity of the materials and erosion of quality control standards spawned problems that harmed artworks over time, introducing a new set of challenges for conservators in the generations to come.

Our Unique Approach To Building Stretchers

Our semi-boutique production process, merges the power of customized tooling with the added precision and quality control of veteran artisans. It is a best-of-both-worlds model distinct from the world of mass-produced, store-bought options.

We cut our stretchers using machine technology and tools, but purposefully work on a manufacturing scale that prioritizes the human factor, with the skill and eye of an experienced craftsman vetting every measurement, every piece of wood, every joint — by hand.

In all our products, especially when it comes to building larger stretchers, the precision and strength of our wood joinery cannot be matched. 

Features Of Our Canvas Stretchers

The unsurpassed reliability we achieve with each Canvas Stretcher breaks down largely to the quality of the materials and the strength and precision of the design.

The Importance of Wood

Wood quality is paramount. We meticulously source and scrutinize every piece of wood that enters our studio. Clear lumber is key and, in our experience over four decades, only certain woods are suitable for making stretcher bars.

Most types of wood will twist to some degree as they age and, unfortunately, finding sufficient quantities of the woods we trust, at the quality grade we demand, has become increasingly difficult over time.

This only means we strive harder to ensure the exceptional.

Basswood

Appalachian Basswood is our primary stretcher bar material. The basswood tree yields lumber that is fairly soft for a true hardwood. Once seasoned, it remains remarkably stable and nearly impervious to warping or twisting even over long periods of time.

The grain tends to be notably fine, straight, and uniform overall; Basswood is a potent blend of strength and stability despite being lightweight.

From there, building quality stretcher bars becomes about crafting the right profile.

Eastern White Pine

Solely used for our continuous bevel and Italian and French conservator-driven styles of canvas stretchers. Previously Simon Liu, Inc. has used sugar pine for its products for conservation. However, since 2021 due to environmental and conservation changes, we have used eastern white pine, the best option for stretcher bars of this style.

Stretcher Bar Profiles

Among the various technical features of canvas stretchers, understanding stretcher bar profiles can be a challenge. What are the advantages of a continuous bevel? Why select an L-shaped profile?

For one thing, there always has to be some degree of a stretcher bar bevel, even just a slight one, to separate the canvas from resting directly on the stretcher, which can cause aesthetic problems to the canvas surface, especially over time. Similarly, the crossbars are always set back a ways, so they don’t become visible through the canvas.

A continuous bevel supports thinner profiles. With work from the 19th century and older, a thinner profile is often necessary for conservators to fit the piece in its original frame and conservators will require a thinner profile.

An L-shaped profile, on the other hand, is usually very deep, providing more separation. This is more common for modern or contemporary work.

A thinner profile will be more resistant to twisting, but another hedge that’s worth incorporating is sealing your stretcher bars.

Sealing

While sealing is not an absolute necessity with Canvas Stretchers, we still recommend the added protection it provides. Whether using a clear shellac, B-I-N® (a white shellac-based primer-sealer), or Camger (a water-based polyurethane), sealing the wood helps prevent drying out and significantly reduces the possibility of future twisting.

All wood can invariably move at least slightly over great lengths of time, and nothing is fool-proof. But sealing considerably fortifies stability.

Canvas Stretcher Types

For most artists, galleries and institutions, and collectors, our American Traditional Stretcher, Mechanical Stretcher, or our innovative A-Liu-Minum Stretcher options will meet their art support needs. However, with the same uncompromising dedication to quality and longevity, more specialized varieties are available. Coveted by conservators, these options include our French Style Stretcher, Italian Style Stretcher. For our clients who prefer to paint outside of the box, our customized shapes are available to collaborate on.

Stretchers are able to be constructed as foldable when transportation or size constraints are involved. Please check out our FAQ’s page for more information.