As printed papers, banners, packages are pervasive, so is the recognition that they will fade over time due to exposure to light, pollutants and handling. However, few people can easily quantify the degree of fading that has already occurred until it is well-advanced and often irreversible. An assurance of the accuracy / validity of color samples is especially important in the commercial realm. For example, a user of a Pantone book or an alternative set of printed reference color samples needs to know that the sample colors are still accurate and valid. The only currently used marker is a printed date. We propose the use of a simple visual reference marker that is based on a side-by-side color comparison. We used our understanding of the fading process of printed material to create a novel type of fade sensors. These sensors are based on the concept that inks fade non-linearly and at different rates. Selecting the right combination of inks enables us to display visual cues or messages at various stages of the fading process. In our first experiment, we accumulated empirical fade data for several combinations of HP original ink and media and 3rd party company refill ink and media. We developed algorithms and visualization programs to analyze a dataset of 536 colors per ink and media sets through 80 years of fading and reduced the pool of marker color candidates to 20-40. In this initial phase, the final selection was done manually to account for the directionality of the color difference (luminance, chrominance, or hue) and to incorporate previous research on text readability. In the future we are planning to automate the final selection process. Adding our sensor to a set of reference color samples would visually communicate that the colors samples are not valid anymore and that the set needs to be replaced.