Preparation for Freeze Drying of wet paper documents
- Wet Paper can be recovered in most cases if the following steps are taken immediately.
- Generally, it is important to get the documents out of the wet space and to a stable environment – one with air movement – as soon a possible. Mold sets in within 48 hours if the temperature is warm and there is no air movement.
- No attempt should be made to open books or separate file folders or documents.
- If the wet documents are in a filing cabinet or are in the open, place the wet paper in a new, dry records storage box.
- If the wet documents are in a wet records storage box, remove the wet paper from the wet box and place the wet paper in a new, dry records storage box – one without any markings on it.
- The new box should be a triple/double walled box (triple layer on the ends, double on the sides and bottom and a single-wall shoebox type lid) which will provide added strength to protect the contents. If the wet paper documents are in a larger records storage box (10x12x24 or 10x15x24), it is highly recommended that the contents be split into two one-cube boxes with a “box 1 of 2” and “box 2 of 2” notation as to the exact contents and includes the former numbering scheme.
- All plastics are to be removed from the box as heat will be introduced for the freeze-drying process. This includes three-ring binders or separators for sheets. Take the wet documents out of the binders and discard the binder.
- If a conventional records storage box is not available, do not use a box that exceeds 14 inches in height.
- Place 12 to 13 inches of wet paper in each dry box – standing the paper vertically, up on its side so they will not lay flat. If the paper is laid flat, it will be difficult if not impossible to separate the pages. If the paper is in file folders, leave them in the folder but stand them up.
- Every box should be clearly marked on the outside of the box with a good permanent, waterproof magic marker, with the writing on the side of the box where the hand hole is (not on the top) as to the contents of the box and any other significant information that will assist later in determining what the box contains without looking inside.
- If the wet box has any hand-written customer markings on the front of the box or has a barcode number, the markings should hand-written on the front of the new box and the barcode number handwritten on the front of the new box. The entire front of the wet box should be cut off of the wet box and laid flat on the top of the wet documents of the new box under the lid – just as a precaution.
- If wet books are included, place them in the box vertically with the spine or bindings down, against the box bottom. The paper should not be used to separate the books unless the cover ink is bleeding.
- Boxes should not be stacked on top of each other once they are loaded with wet paper. They should be placed on a pallet and not shrink-wrapped.
- The freezing process is the most critical step in preparing the documents for stabilization and should be accomplished as soon as possible. The boxes should be initially delivered to a blast freezer company who will quickly freeze the paper. If a blast freezer is not available, any level of freezing is better than none. A blast freezer takes the contents quickly to -20 F and after 48 hours, the boxes can be taken to a freezer that keeps the contents at zero F. Preferably, the boxes should then be kept at zero degrees until they are ready to be transported to freeze-drying chambers, which are in another city.
- It is important that you inventory and prioritize each box involved, prior to committing to freeze dry the boxes. If the retention period for the box is near, it may be more economical for you to keep the box in the freezer until the retention period lapses rather than freeze-drying the box now. If the box is needed later, it will take approximately three weeks to move the box to the freeze-drying vendor, complete the process of freeze-drying and prepare the box for use.
- Refrigerated transportation will be utilized to deliver the boxes to the freeze-drying chambers, which are located in another city.
- The freeze drying process utilizes sublimation, which is the process of changing frozen water (ice) in the documents to a vapor, bypassing the liquid state. The documents are placed in a large vacuum chamber where heat is introduced and vapor is simultaneously removed. Freeze drying will also help to remove stains and odors.
- Freeze-drying requires approximately 14 days to complete the sublimation process. When the boxes are removed, they will be allowed to sit for a few days to regain their natural moisture content, which is about six (6) percent. After this time, documents can be opened and cleaned if necessary. Remember that many documents were wetted by “dirty water” and may need individual cleaning after being dried. After the drying process, they are reboxed for the return trip.
Please contact us immediately if you are in need of restoring or securely disposing of wet documents at (615) 242-9600.