With the decision of the 1997 Montreal Amendment to the Montreal Protocol to phase out the use of methyl bromide in developed countries by 2005, interest has been renewed in reappraising thermal methods for eradicating museum pests. Though a quantity of literature exists which investigates the effects of heat and cold on insect mortality, very little research has been published on the effect that the standard freezing procedure and the Thermo Lignum (TM) process have on object materials, though this is obviously the greater concern for the museum professional. This article reports on a series of investigations of ethnographic and natural history materials, using optical and scanning electron microscopy, Fourier transform infrared spectrometry, and tensile testing to establish whether physical and/or chemical damage occurred. Results from this work suggest that a broader range of object materials than usually considered acceptable could be successfully treated by one or other of these means. Suggestions for further research are given.