Details:
Summary:
One effect that can cause errors in many reflectance spectrophotometers and densitometers used to measure printed products is translucent blurring. This error results when some part of the instrument structure intercepts a portion of the light reflected by the sample and preventing it from being seen by the detector. The magnitude of this error is a function of both the translucency of the sample being measured and the size of the sample area being measured. Many instruments designed for the graphic arts place a target aperture on the sample area being measured. Many of the paper and ink combinations commonly measured are sufficiently translucent to give significant measurement errors when small aperture plates are used. Many instruments designed for the graphic arts place a target aperture on the sample area being measured. Many of the paper and ink combinations commonly measured are sufficiently translucent to give significant measurement errors when small aperture plates are used. This paper compares measurements of a number of plastic samples with different white pigment loading. Each sample is measured with a 45/0 spectrophotometer using several different size plates.