Changes in chemical, microstructural, and barrier properties of two commonly used and commercially available waxes - a microcrystalline wax (Renaissance wax) and a microcrystalline and carnauba blended wax (Butcher's Boston Polish Amber Paste Wax) - for the prevention of corrosion on outdoor metalwork were investigated. The waxes were applied to both plain and patinated substrates of bronze and steel, and properties of the films were measured before and after weathering. Accelerated weathering was performed by accelerated UV-B illumination/condensation and outdoor weathering under standard South Florida exposures and in Portland, OR. Comparison of Fourier transformed micro-infrared and nuclear magnetic resonance spectra enabled characterization of chemical functional groups of these waxes as they weathered and showed relative increases in methylene character suggestive of cross-linking, appearance of terminal vinyl bands suggestive of chain-scission, and evidence of oxidative film damage. After annealing, microstructural changes were observed by thin-film X-ray diffraction and showed a decrease in crystallinity, which indicates a decrease in barrier properties. The barrier properties of the wax films after weathering were studied by electrochemical impedance spectroscopy and equivalent electrical circuits provided insights into the physical state of the films. The electrochemical impedance spectroscopy data showed that the permittivity of the weathered waxed panels increased, which was observed as a decrease in coating resistance and an increase in coating capacitance. Photographic documentation of the substrates showed extensive visible corrosion upon weathering. Our results demonstrate that waxed metal panels exposed outdoors do not have a period of stability when the protective qualities of the film do not change. This suggests that while waxes are commonly used to protect against corrosion, their barrier properties are affected by flaws in the microstructure and their susceptibility to chemical alteration during weathering. Results from a blind study with professional conservators as the participants are presented, to elucidate how they rank the importance of such factors as gloss and working lifetime when selecting protective coatings.