This 18x36 size is in the 2:1 Domino. Medium weight Belgian Linen - primed weight: 13 oz.. It's sized and primed with an archival quality oil primer, impervious to paints leaching through that harm the fabric. For oils or alkyds only. It's highly absorbent and has excellent qualities of luminosity. It has a warm yellowish hue and is an extraordinary painting surface! Linen is strong and it's natural oils keep it flexible and prevents disintegration. The surface has a smoother tooth, although, not portrait. There is a 5/16" gap between the canvas and frame, eliminating the unwanted lines that occur when the gap is less. We never use finger joints in our wood frames, which often fail under tension and over time - the glue joints give up, and are unsuitable for paintings intended to last for centuries. Patented 3.25" wide heavy duty keyable cross braces allow the canvas frame to be tensioned in the middle, where the tension is needed the most! The Stretcher Bars are slotted in the center to accept the cross braces. Due to our unique design, the cross braces provide maximum rigidity and may be removed, if desired. Both corner keys and brace keys are pre-installed. Stretched using our proprietary MuseumWrap method, producing a drum-tight-stretch, up to 50% tighter than other methods, and with balanced tension across the surface. The corners are uncut and neatly folded, making it possible to remove and re-stretch the canvas on the same size frame.