That depends. If the design is to be printed, then it can be enlarged in the digital design file (although if it is a Photoshop file, the resolution must be maintained, creating an enormous file.)
But if the design is to be SEWN (or “appliquéd”) on a fabric banner, like many large museum banners are made, the process is more involved. Appliqué is the technique of sewing pieces of color fabric onto a fabric background. Nothing is printed; even the tiniest details are hand-stitched by skilled craftspeople using sewing machines.
What is required is to make a full-size sewing pattern. That’s right, a paper sewing pattern 35 feet tall by 25 feet wide, from a piece of artwork one foot tall. I used to make these patterns by hand-drawing the graphics by eye (no projector) on large strips of paper. But then a process was invented utilizing the computer.
Today, the graphics are painstakingly traced in Adobe Illustrator, transforming “bit-mapped” art (made of tiny pixels) into “vector” art (outlined shapes). Since vector art can be enlarged to any size with no loss of quality, the outlined graphics can be scaled proportionately and then printed with a plotter, onto rolls of paper 5 feet wide by 25 feet long. After creating seven different paper panels, the sewing pattern is completed.
Left: The full-size sewing pattern. Red lines indicate 5' x 25' panels. Right: The completed appliqué banner, installed.
The pattern is traced onto the colored fabrics, which are then pinned into position, sewn, and the excess cut away, a process very similar to making a quilt. The 5-foot wide panels are joined together, making a banner so large it really can’t be seen inside the sewing shop; only when it is mounted onto the building facade can the entire design be viewed!
Close-up of the appliqué method.
Large exterior banners are finished with interior ropes, grommets and wind vents so they can withstand all weather conditions. They are something to behold: bright, colorful, catching the sun, moving with the wind...and entirely sewn by hand!