For many years, densitometry has been the measurement of choice for photographic permanence investigations. With the availability of affordable colorimeters, CIELab data are often used instead. To investigate if both types of measurement are applicable to permanence investigations, Status A densitometry, CIELab and full spectral readings were performed on samples in accelerated light stability, pollutant fading and thermal stability tests. The quality of the prediction between the two measurement methods is compared. For monochrome wedges and in images where primarily one colorant fades much faster than the others CIELab ΔE gave similar predictions as density. Even in gray wedges and when several colorants fade at similar rate, densitometry did not prove much superior to CIELab ΔE. Predictions based on CIELab a* and b* provided even better results than those based on ΔE. Contrary to CIELab data, densitometry measurements are suited to investigate fade mechanisms and distinguish between the contribution of the single colorants to overall fading. However, the full spectra available from spectral densitometers make those even more valuable tools in elucidating colorant reactions.