Simone K. Johnson
Yuhong Chen

Introduction

Our project looked at the color spectroscopy of pigmented substances such as makeup, food coloring, and paint. Using the color spectrometer, we tested each sample for the wavelengths red (645 nm), yellow (585 nm), green (560 nm), and blue (470 nm). Doing this gives a more thorough understanding of the color composition of each sample, and what certain pigmentations reflect and absorb.

This was done using a Vernier ALTA® II Reflectance Spectrometer and logging the data into Excel. We swatched each substance onto a 10 cm by 10 cm square. The spectrometer emits a colored LED light of a certain wavelength onto the sample of swatched pigment and measures the absorbance based on wavelength.

Results: Absorption Readings

(lower number = higher absorbance, higher number = higher reflectance)

Hypothesis, Analysis of Results and Conclusions

The original hypothesis was that the more expensive products would have more pigmentation and return higher numbers on average. However, the conclusion reached was that more expensive products did not necessarily lead to higher pigmentations. The blue wavelengths were noticeably low in every sample, especially the red pigmented colors. There were high variations in lipstick colors. In seven of the nine lipstick colors tested, there was a very low amount of yellow, green and/or blue. There was high red reflectance in all of the samples, as they were red lipsticks. The Urban Decay Crimson lipstick and the Artist Rouge lipstick were the only two lipsticks that had high levels of blue, green, yellow, and red. This high mix of multiple colors could suggest that the pigmentation is stronger or more complex, as it is composed of more colors.

In regards to the cadmium family of oil paint, ‘true’ cadmium pigment is toxic and more expensive. As a result, we acquired two substitutes of ‘cadmium yellow hue’ that use different, often cheaper pigments to emulate the color of cadmium. However, the colors from both brands had slight differentiation on paper and this was evident in the lower reflectance of blues, and the too-high-or-too-low reflectances of yellow and green. The shapes of the spectrums appear similar enough for the imitation shades to be considered good substitutes, but provide further implications on the effect of pigment on color payoff as well as safety of use.

This project taught us about color spectroscopy and interaction between light and color, while giving us an understanding of color dynamics, wavelengths, and properties. We learned about reflective and absorbed lights in the visible light part of the electromagnetic spectrum and how that affects how people interact with color and pigmentation in commercial products. This project also taught us how to work with color spectrometers and equipment usually used for physics projects.

What we learned was that high end did not necessarily translate to higher pigmentation, and higher pigmentation did not necessarily translate to higher quality — that there were more factors that contributed to price and quality, such as the safety, availability, and formulation of the vehicle carrying the pigment all contributed to the ‘quality’ of a pigmented substance. Also, specific shades made up of varying color compositions are often sought after more than shades that are highly concentrated in one color.

Repetition and Continuation

If we did this experiment again, we would probably organize by the pigments in the ingredients list. Unfortunately, due to the makeup industry’s regulations, companies do not have to release all specific information on their pigments and formulas — this can be something that can be further investigated by acquiring pure pigments and trying to match the color composition through the use of more spectrophotometry and some chemistry.

If we were to do this project again, we would probably collect more samples to have more varied data with different colors. We would also be able to buy pure pigments to mix for new colors and make comparisons to the collected samples.

These results are related to current technological developments because it can be used in various ways to advance pigment manufacturing. Color spectroscopy can be used in quality control to ensure consistency during manufacture. Further, color spectroscopy can be used in the analysis of many more pigments, organic, inorganic, or synthetic, which can be used by chemists as well. Last, the emergence of different methods — such as makeup printers and color scanning ink pens — combined with the use of color spectroscopy might revolutionize the industries of art supply, makeup, and other pigmented substances.