Friday, 8 February 2013

More about Pesticides

In a previous blog post, I wrote about pesticide residues on museum objects, and the work being done as part of this project to attempt to identify pesticide residues on objects from the Cook-voyage collections at the Pitt Rivers Museum.  

Detail of barkcloth 1886.1.1240, showing staining and associated damage

This week, I've been taking more samples to send off for analysis.  It has been noticeable that many of the barkcloths I've conserved so far have had areas of staining on them, often associated with damage to the structure and weakening in the stained area.  We're starting to suspect that this damage might be the result of the application of pesticides in the past.  

One of the problems when thinking about pesticides and their effects is that the chemicals were available in many different formulations, with lots of ways of applying them.  These methods include dissolving pesticides in water or other solvents and spraying or misting objects, or the objects could just have been dusted with a powder. The same pesticide could have been applied in different ways at different times.

Whilst we understand that the past use of pesticides on museum collections has saved them from the devastating effects of insect damage, and, we suspect, in many cases, continues to do so, the effects of these pesticides both on objects and on those who work with the collections are not yet properly understood.

A 30x30cm area of barkcloth framed within a temporary border

Here, I am taking samples of surface residues from a large barkcloth collected in Tahiti on Cook's second voyage.  The barkcloth is about seven meters long, and there are areas of staining in several places.  I've made a frame so that I can take surface swabs from an 30cm by 30cm section - this may help us to make a rough estimate of how much pesticide remains on the surface of the entire barkcloth.

Using swabs barely dampened with distilled water to remove residues from the surface of the barkcloth