Freeze-drying

Smart and gentle moisture extraction

In order to prevent document damage resulting from water intrusion, Rhenus subjects the material to be restored to a freeze-drying process that is comprised of two main stages:

As a preparatory step, the documents are flash-frozen in a Rhenus-owned deep-freeze facility. Then they will be transported to our freeze-drying vacuum chambers to undergo restoration treatment.

Freeze-drying is a preservation technique whereby water is removed under vacuum while the material remains frozen.

• It is a gentle method ensuring that the information-carrying paper will be protected throughout the document recovery process.
• Undesired side effects (collateral damage) such as leaching of writing ink, blocking (i.e. adhesion of leaves, bleeding of printer’s ink or corrosion of metal parts etc.) do not usually occur with this method.
• Document legibility will thus be reliably preserved.

Thanks to the use of state-of-the-art communications technology, the equipment employed by Rhenus is at all times safeguarded against unforeseen downtimes so that power outage and other incidents will not be an issue. The facilities are provided with an automated malfunction detection and alarm system working in tandem with an emergency power supply. This allows continuous operation and ensures that the cold chain will not be broken until the dry-freezing process has been successfully completed.