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Pam Freezing to -80 C seems a drastic method for getting rid of spiders in a collection of bones. I wonder whether there might be some weakening of the bone, due to thermal stress and expansion of moisture in the bone. DNA survives freezing, but if residual DNA is of interest you would need to enquire about the effects of freezing to -80 C. I am not sure from your email whether decontamination by an unknown method has already happened, or whether you still have a choice. Gamma irradiation is often used by quarantine authorities as a catch-all decontaminant. That would destroy all living things in and on the bones, but unfortunately destroy also any residual DNA. If the problem is solely spiders, then methyl bromide fumigation, inside a chamber, would be simple and effective. It is widely used by quarantine authorities against arthropods. I imagine it would do no harm to the bones, when it comes to any subsequent analysis. It would be interesting to hear about the experience of others. Richard On 27/12/2011 00:27, Pam Crabtree wrote: > Dear Zooarchers, > > Happy Holidays and best wishes for peace and joy in the New Year. I have a question for you. Since November I have been expecting a small collection of faunal material that was excavated by one of my NYU colleagues from the Institute for the Study of the Ancient World. After the bones had been cleaned and bagged in the field, some spiders apparently slipped into the boxes. The boxes with the fauna were seized by the USDA and sent to UC Riverside for decontamination. One possible means of decontamination is to freeze the bones down to minus 80 degrees C. Does anyone have any experience with this method? How badly will it damage the bones? > > Many thanks for any help you can give me. > > Happy New year, Pam Crabtree