Multifunctional Vacuum Chamber

3. Drying in controlled atmosphere

Books are dried under normal atmospheric pressure with air, or other gas, circulating in the chamber treated to the required temperature and humidity. Using specific gas prevents e.g. spreading of mildew in documents even under higher temperatures. It allows drying documents for very long time without risking degradation. This method is used for drying documents that cannot be dried using one of the previous methods.

Multifunctional vacuum chamber is used for preserving precious historic documents (books, archival documents etc.) damaged by water during breakdowns and natural disasters. In case of soaking it is necessary to deeply freeze the damaged documents (from -60 to -30°C) using sufficient intensity freezing process. This will lead to formation of very fine ice crystals that will minimize the damaging done to the cellulose in paper, structure of skins, parchments and other materials. It is possible to preserve frozen documents for relatively long time even under higher temperatures (from -15 to -6°C) until drying and restoring.

Freezing will prevent further degradation of the paper due to spreading of mildew and overall decay of the paper. Collections of various institutions contain documents with different types of papers, parchments and other materials requiring different technologies of drying or even disinfecting with suitable substance. The following non-invasive methods of drying in multifunctional vacuum chamber are particularly suitable:

1. Vacuum drying.

A book or an archival document dries out in vacuum but the chamber receives enough heat only to convert water in the book from solid state to liquid. Water than evaporates under lower temperatures that do not lead to degradation of paper.

2. Vacuum freeze drying - lyophilization

Books are dried by sublimation without water being transformed into liquid state. This method of drying is mainly used with documents that are in danger of running color pigments, inks, stamp color etc.

4. Disinfection

Books are exposed to effective disinfectant. Vacuum facilitates spreading of this substance inside of paper block of document in its entire volume.

This chamber is fully automated including a data processing system, data imaging and the possibility to access the measured data via internet in order to enable real-time monitoring of drying or disinfecting processes taking place.

Technical parameters: length 1 600 mm

Diameter 1400 mm

Operating temperature -60 to + 60°C

Inside view

Multifunctional Vacuum Chamber designed for National Library in Prag