Opacity refers to the property of paper which obstructs the passage of light and show-through of printing. This characteristic is expressed as the percentage of visible light that does not pass through a sheet of paper. For example, 98% opacity means that 98% of the light can not pass through the sheet, and is absorbed in or reflected by the paper’s surface. Low opacity means the paper will have more show-through, such as tracing paper. High opacity means there will be less show-through, such as business card stock.
A simple test to check opacity To make a visual comparison of two different sheets of paper, place both of them across the 5 solid bars, positioned so that both sheets will touch in the center. You will easily see which sheet has the greatest opacity. The greater the opacity, the less you will be able to see the solid bars through the sheet.
