quick and non-invasive drying of documents

Prodoc has systems that are able to dry documents, books and archives that use a latest generation freeze dryer.

The freeze-drying process, to which the goods to be recovered are subjected, is physical and does not use chemicals that are potentially harmful to humans or the material to be recovered.

The freeze drying device freezes the paper material and dries it in a vacuum environment. The water passes from the solid state directly to the gaseous one (sublimation).

Freeze drying is advantageous compared to air drying as it reduces the time and materials to be used by 75% and at the same time minimizes the solubilization of the inks and the creation of gores and stains.

The chemical-physical characteristics of the material components remain unaltered because the processes take place at temperatures below 20°C.

Freeze-drying proves to be of great use where it is essential to work under strict conditions of sterility, as neither the growth of bacteria nor enzymatic transformations take place in frozen materials.



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How does freeze-drying work for paper and documents?

Unlike hot, microwave or air drying, freeze drying is the gentlest method, as it avoids damage caused by excessive heat and dries paper materials by restoring their shape without increasing their volume and avoiding warping.

When bound paper material is air-dried there is also a risk of mold spreading unnoticed because the volumes cannot be dried quickly enough.

Freeze drying can be used for books (even with leather or parchment cover), folders and single sheets, almost all materials and photo albums can be freeze dried.

Other materials such as films, microfiches, parchment certificates or sensitive graphics must be individually air dried.

During freeze drying, the material to be dried is placed in the vacuum chamber of the freeze drying system and the process is started.

There are no other mechanical effects on the paper materials to be dried. Our restorers follow procedures and best practices for the treatment of papers, books, folders in such a way that drying takes place uniformly on all materials so as not to alter their state or to leave damp parts that can be easily attacked by molds.

Post freeze-drying treatments

If damage to the material occurred prior to freezing, such as mechanical damage or mold growth, further restoration work is required.

Cracks and tears are closed with Japanese paper, imperfections are filled with matching paper. Infestation with mold or insects must always be subjected to a subsequent dry cleaning.

Damp or wet books, documents or folders, as well as damp or wet paper, are particularly at risk when it comes to mold growth.

Wet cellulose from paper is an optimal nutrient substrate for mold and its spores. When exposed to moisture, mold can begin to arise and grow within hours.

Professional removal of mold from paper and books prevents the risk of damaging valuable cultural objects or important administrative documents. This process works in an environmentally friendly way and without carcinogens. After gentle handling, stocks can be safely reused.

In order to better preserve the materials after treatment, we recommend packaging in protective containers made with non-aging material and with a neutral pH.

The work process in case of water damage

The collected material must be cataloged

each object must be uniquely identified so that it is traceable throughout the recovery process.

Each document is bagged

if possible individually in polyethylene bags suitable for storing archival and book material.

Wet documents are frozen

as quickly as possible to avoid the proliferation of pathogens (molds begin to develop only after 48 hours).

The frozen material is transferred to the laboratory

through the use of refrigerated trucks.

Frozen papers are freeze-dried

process that allows to eliminate excess moisture using sublimation.

A restorer recovers the dry material

through the procedures of cleaning, dusting and smoothing of papers.