Document Recovery Methods: vacuum freeze-drying vs desiccant drying

When water damage threatens critical documents, choosing the right drying method is essential to prevent deterioration. This article explores both methods, outlining their benefits, considerations, and best-use scenarios.

What is vacuum freeze-drying?  

The vacuum freeze-drying process is the most efficient and effective method for drying wet papers and documents containing other materials. 

During this process, the materials are placed in an airtight chamber into which negative vacuum pressure is induced. As a result, the documents go from the frozen state to being dry without ever becoming re-liquefied.

Benefits:

• Most effective on saturated books and documents
• Capable of drying in small or large batches
• Does not lead to distortion or swelling
• Prevents pages from sticking together when used within the first six hours of the initial water damage
• Reduces the need for rebinding
• Lifts soot, dirt, and mud to a document’s surface, making it simpler and less time-consuming to clean
• Aids in odor removal
• No need to remove encapsulating materials or polyester sleeves
• Quicker turnaround when compared with other methods

Considerations:

• Items need to be packed and transferred to a document center
• Drying chambers vary in capacity

When to use vacuum freeze-drying

Vacuum freeze-drying is the best solution for recovering water-damaged materials, including books, bound documents, historical archives, collections, and oversized items like blueprints and drawings. 

This method is effective for any level of moisture damage, preventing warping, swelling, and further deterioration. It is especially useful for delicate or irreplaceable documents that require careful handling to maintain their integrity.

What is desiccant air drying?

Desiccant air drying begins with freezing documents, then placing them on racks while desiccant dehumidifiers maintain a controlled environment at 68ºF and 12% humidity. This process continuously removes moisture and typically takes one to seven days, depending on the volume and saturation level.

Benefits:

• Documents may be accessible during the drying process if work is performed on-site
• Books and documents on the shelves
• Drying onsite may help dry out the building overall
• Easily adaptable to projects of any scale or volume

Considerations:

• May cause documents and books to expand or distort, affecting the quality of the result
• Not effective in addressing books or documents affected by mold
• Documents and books must be removed from sleeves
• More labor-intensive. Some documents may need to be spread out, and books may need to be fanned out or pages interleaved
• Bound materials can be affected and get misaligned

When to use desiccant air drying?

Desiccant air-drying is ideal for materials that cannot be moved off-site, such as critical banking and government documents, as well as sensitive audio and video materials. This method is especially effective for drying photos, X-rays, and other emulsion-based media, helping to preserve their integrity while preventing further damage from moisture exposure.

Polygon uses state-of-the-art vacuum freeze-drying chambers that use negative pressure to create the most effective drying solution for certain materials and projects. Polygon has also perfected the use of a desiccant air dry distribution system. This energy-saving technology system allows Polygon to provide customers with real-time access to documents as they complete reprocessing – a major advantage when trying to maintain the activities of a company or organization during a disaster.

Learn more about our document recovery process here.