12x21 3D Pro 3.5" Deep K3 Stretcher Frame Kit

True Paper Size Proportion - 12x21 Size

This interesting palindromic 12x21 size is not based on any specific proportion, but this one is based on the 7:4 ratio.

Explore other sizes in this same 7:4 aspect ratio:

11x17 • 13x19 • 17x22 • 22x34 • 28x40 • 34x44

• Super strong 3D™ Pro K3™ Stretcher Bar is a very popular among contemporary artists whose painting will be displayed without a frame.
• For this 12x21 large size frame, the frame provides the ultimate foundation for your art with increased strength and stability
• Provides a 3.5" deep stretched canvas which makes a bold and commanding display
• 1-1/4" wide Stretcher Bars
• All Bars have an exclusive groove on the inside perimeter of the frame to which cross braces and Diamond Corner Braces attach
• Solid Ponderosa Pine or Fir from the Pacific Northwest

3D™ Pro 3.5 Stretcher Bar • 1/2" Canvas Clearance

1/2" Canvas Clearance is the space between the Bar and the canvas. Generally speaking, more clearance reduces the risk of the canvas touching the wood and creating unsightly lines during painting. Our design provides the optimal clearance so as not to impact your painting, but still leaving enough wood to the maximize strength of the Stretcher Bar.

• Produces a 3.5" deep stretched canvas (Actual depth is slightly thinner)
• 1.25" wide Stretcher Bar
• All Bars have an exclusive groove on the inside perimeter of the frame to which cross braces and Diamond Corner Braces attach
• Solid Ponderosa Pine or Fir from the Pacific Northwest

Solid Wood is Archival - Finger Jointed Wood is Not

We only use Solid Wood to build our Stretcher Bars because a solid piece of wood will last indefinitely. When we speak of archival value, it's not just the paint you use and the quality of your canvas and ground, even the wood choices manufacturers make are part of the archival process.

The principal reason manufactures use finger jointed wood is reduce cost, not increase archival value. Wood constantly grows and shrinks when the environment becomes hotter, or colder, or more humid, or more dry. Because finger jointed wood is made-up of multiple and varied pieces of wood, with varying grain patterns and densities, they each absorb and shed moisture at varying rates, which works on the glue joints that hold them together, causing the wood to bow and the joints to eventually fail, and certainly not consistent with increasing the archival value of your artwork frame support.

As a manufacturer, we do our part to conserve as much wood as possible, and still provide a quality made product that will out-perform any other in the marketplace.

Our Ecosystem Depends on Healthy Forests

Forests play a vital role in our planet's ecosystem. They absorb carbon dioxide, filter air and water, and provide habitat for countless species of plants and animals. By using sustainably sourced lumber, we can help to protect these important ecosystems and ensure that they continue to provide these valuable services for generations to come.

22x31 is the Canvas Size Needed for this 12x21 Frame

Please note that you will need a canvas that is at least 10 Inches larger than the actual frame size to ensure proper stretching. This will provide ample material to stretch the canvas and attach it to the back of the frame. If you prefer to attach the canvas from the edge of the stretcher frame, you can reduce the size of your canvas by approximately 3/4" all the way around the frame. This will allow you to paint on the edge of the canvas and hang your artwork without needing a separate picture frame. And, if you ever need to remove the canvas from the frame and re-attach it, you'll have enough material to do that too.

Tight'n'Up™ Liquid Canvas Retensioner

One of our most appreciated products helps make your canvas tighter! Stretching a canvas tightly can be a challenge. Our Frame Kits include the Corner and Brace Keys that you will need to add tension, but Tight'n'Up™ Liquid Canvas Re-Tensioner is a way that you can use to add tension to the canvas without needed to use the keys. It canvas be sprayed on the back of a canvas to repair most canvas tension issues.

With Tight'n'Up™, you can add tension to just a small area, or a large area. Simply spray it lightly on the back and brush it into the canvas, and within seconds, your canvas becomes tighter and stays tighter. The more you use, the tighter it gets. Recommended for acrylic primed cotton or linen canvas. We do not recommend it for oil primed canvas because there are simply too many different types of oil primed canvas, but used conservatively at your own risk, it will tension any canvas.

With deep family ties and a legacy spanning since 1965 in California, Masterpiece® has been the epitome of unmatched quality in Stretcher Bars across North America. Our commitment to pioneering excellence has crowned us as the forerunners in the world of professional fine-art canvases. Bolstered by our patented innovations, our products exude a caliber that's in a league of its own. One touch, and the unparalleled quality becomes palpable, leaving an indelible impression on your clients and all future admirers of your art.