Using BEST Medium-Duty Stretcher Bar - 34" ensures your stretched canvas will be smooth. White pine wood is used to make this stretcher bar. Its rolled edge helps to keep the canvas smooth and even, allowing it to look its best. Ghost impressions are kept to a minimum by keeping the canvas about 1/2 inch away from the edge of the bar. The canvas an artist uses is a key factor in producing a work of art is worthy of the creative process. Using these stretcher bars helps ensure you begin with the perfect canvas.