MEASUREMENT OF CASE EXCHANGE RATES AND THE USE OF SUCH MEASUREMENTS

Hubertus Ankersmit⁺, Maximiliano Lebidinsky, and Simon F. Watts

School of Biological and Molecular Sciences, Oxford Brookes University
Instituut Collectie Nederland / Netherlands Institute for Cultural Heritage (ICN) ⁺

PART 1: ABSTRACT

The results of some case exchange experiments is reported. The case used for these experiments had a volume of 1.5 m³ and composed of 4mm polycarbonate sheets with pre-drilled holes covered with duck tape, (See slides from presentation).

N₂O, Temperature and relative humidity were measured at various points inside and outside the case. The N₂O was squirted into the case (maximum total concentration was 5%) and the concentrations of N₂O, RH and temperature measured with time. This set-up was chosen as it gives the basis of a simple and economic method for the measurement and interpretation of case exchange rates in working (i.e. with artefacts) museum cases.

Data from the laboratory case was presented and showed a number of characteristics:

1. The decay of the levels of RH and N₂O were broadly consistent
2. The data showed a very interesting second order dependance (i.e. 1/[N₂O] vs time) was a straight line
3. The determined exchange rate varied not only with the cross section of the holes, but also as a function of the position of the holes

Click here for Part 2: Slides from presentation

Ankersmit, H.
Instituut Collectie Nederland
Gabriel Metsustraat 8
Postbus 76709
1070 KA Amsterdam

Lebidinsky, M. and Watts, S.F.*
School of Biological and Molecular Sciences
Oxford Brookes University
Headington, Oxford, UK
OX3 0BP
E-mail: sfwatts@brookes.ac.uk*

(*): Author to whom correspondence may be addressed: