5 CONCLUSIONS

The diffusion constant of the common atmospheric pollutant, SO2, in the boxboards used to make up some archival boxes was determined to be 0.004 cm2/sec or less for gas concentrations of 10–150 ppm. Although these gas concentrations are much higher than those found normally in the atmosphere, these data show the order of magnitude of diffusion though these boxboards. Further, the glue layer used to make up this composite boxboard may have a significant effect on the diffusion in some boxboards.

When values for the diffusion constant of NARA boxboards are put into the Passaglia models, we find that the pollutant flow into a prototypical archival box is controlled by the diffusion through the boxboard.

ACKNOWLEDGEMENTS

Support for this project came from a grant from the National Archives and Records Administration (NARA), Washington, D.C. The authors would also like to thank W. Hollinger of Conservation Resources International, Springfield, Va., for providing samples and discussions on the boxboards and manufacturing process. The authors also appreciate discussion with E. Passaglia of National Institute for Standards and Technology (retired) and W. K. Wilson of NIST (retired) and NARA.

Contribution of the National Institute of Standards and Technology. Not subject of copyright.