Effects of Drying Methods

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Comparison of Drying Methods Hilary A. Kaplan
and Kathleen A. Ludwig United States National
Archives and Records Administration
IFLA Pre-Conference 2003
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SWELLING DISTORTION
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METAL FASTENER CORROSION
PARCHMENTS STICKING TOGETHER
WHAT WATER DOES TO PAPER AND
PARCHMENT
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BLEEDING MEDIA DYES
WHAT WATER DOES TO PAPER AND
PARCHMENT
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MOLD
DISCOLORATION FROM DEGRADATION BY-PRODUCTS
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• Comparisons and Observations
• In-house
• Air drying
• Dehumidification drying
• Off-site by vendor
• Dehumidification drying
• Vacuum Freeze-drying
• Patented Vacuum Freeze-drying

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PATENTED VACUUM FREEZE-DRY PROCESS
AIR-DRYING
VACUUM THERMAL DRYING
Book Before Book After
VACUUM FREEZE-DRYING
DEHUMIDIFICATION DRYING
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Diverse media and formats often contained in one
box
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Expendables
Boxes packed in the same order with similar
records
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All boxes were immersed in 5 cm of water for 24
hours
Half of the boxes also received water from
above
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Records Drained for 2 Hours Before Freezing
Records Wrapped Prior to Freezing
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PACKING FOR FREEZING
LINING INTERIOR OR EXTERIOR WITH PLASTIC
INTERLEAVING BETWEEN VOLUMES
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• Variables
• All compared records were not identical in
  structure and media
• Differential wetting may have occurred at the
  outset
• Handling and environmental conditions may have
  varied greatly

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Thawing Prior to Air Drying
4 days at -20 C
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AIR DRYING
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Air Drying on Blotters
Interleaving with Polyester
Non-Woven Fabric
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Plastic Must be Removed for Effective Air
Circulation
Note that
Encapsulation May Not Prevent Moisture Intrusion
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Air Drying Conditions for a 2 Day Period Average
Temperature 21-22 º C
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Trucks Holding Frozen Records
for Dehumidification
Dehumidification-Drying Chamber
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Closer view of Supported Books
Items on Dehumidification-Drying Rack
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Dehumidification-drying After Thawing
Curl After 48 Hours of
Dehumidification-drying
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After dehumidification-drying, records no longer
fit in their 2 original boxes.
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Dehumidification-drying IN-SITU
(Items never removed from their box)
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Delmhorst P-2000 moisture meter
with 30.5 cm probe

Moisture content was measured daily and recorded
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T and RH of the On-Site Dehumidification Drying
Chamber
for the 13 day period 2/22/02-3/7/02 Average
Temperature 21-37 º C
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Mold grew during dehumidification- drying
in-situ. The wet samples were eliminated from
further comparison.
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Some records were returned without labeling
information
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Original order altered
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Original labels were returned in new boxes
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On-site Dehumidification
Vendor Dehumidification
Air dry
Control Vacuum Freeze-dry
Patented Vacuum Freeze-dry

Order in Folder Altered
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Distortion in Identical Groups of
Paper Records Dried Differently
Vacuum Freeze-Dry
Air Dry
Control Patented Vacuum
Dehumidification Freeze-Dry Vendor On
Site
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Vacuum Freeze-Dry
Patented Freeze-Dry
Control
Air Dry
Bound Records
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Control
Air Dry
Patented Vacuum Freeze-Dry
Vacuum Freeze-Dry
Ability to Open Flat
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Vacuum Freeze-Dry
Patented Vacuum Freeze-Dry.
Vendor Dehumidi -fication
On-Site Dehumidi-fication
Air Dry
Control
Fastened Bound Records
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Patented Vacuum Freeze-Dry
Vacuum Freeze-Dry
On-Site Dehumidification
Vendor Dehumidification
Air Dry
Control
Pamphlet Bindings
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Changes occurred to Vinyl Cover in the Patented
Vacuum Freeze-Dry Process
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Vendor Dehumidification
Control
MAY LEAVE IN PLACE
Vacuum Freeze-Dry
On-Site Dehumidification
Patented Vacuum Freeze-dry .
Air Dry
SHRINK-WRAP FILM
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Interleaving Required to Prevent Adhesion of
Coated Paper During Air and Dehumidification-Dryin
g
On-Site Dehumidification
Air Dry
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Patented Vacuum Freeze-Dry .
Vacuum Freeze-Dry
No interleaving required for coated
paper in Vacuum Freeze-drying processes
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Vendor Dehumidification
On-site Dehumidification
Air dry
Control Vacuum Freeze-dry
Patented VFD
Rolled Records
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CONTROL PATENTED VACUUM FREEZE-DRY
BEFORE
AFTER
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PATENTED VACUUM FREEZE-DRY VACUUM FREEZE-DRY
AIR DRY
Delamination of cellulose nitrate coating
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On-site Dehumidification
Control
Air Dry
Patented Vacuum Freeze-Dry .
Vendor Dehumidification
Vacuum Freeze-Dry
POLYESTER L-SLEEVES
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Only Vacuum Freeze-Drying Processes Were
Successful in Drying Encapsulated Items
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Air Drying
Dehumidification Drying
Drying Ineffective When Items Left in Sleeves
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Metal Fasteners Corroded Before Records Dried
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LESSONS LEARNED

• Contact vendors BEFORE an event strikes.
• Gain an understanding of the .PARTICULAR
  PROCESSES AVAILABLE.
• Check references. EVALUATE CAREFULLY.
• Specify EXACT TREATMENT. Make.sure
  terminology is clear.

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LESSONS LEARNED (2)

• Obtain a LISTING OF FEES for services.
• MINIMUM CHARGE
• ADDITIONAL FEES
• COSTS FOR RETURN SHIPPING
• One US record storage box gt 1 cubic foot One
  US storage box billed as 1.2 cubic feet

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LESSONS LEARNED (3)

• Intellectual control and original order MAY
  NOT BE PRESERVED
  unless specified.
• Indicate how groupings of records are to be
  re-associated if fastener, folder, or adhesive
  attachment cannot be retained with records.

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LESSONS LEARNED (4)

• Specify desired label information and...
  replacement box quality.
• Shipping may contribute to records
  .distortion and length of exposure to moisture
• DESPITE ALL EFFORTS, RECORDS MAY BE LOST

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Real Life Disaster Events
ASSEMBLING AND LABELING NEW BOXES
HUMAN CHAIN
PROPER STACKING ONTO PALLETS
LOADING OF FREEZER TRUCK
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Air Drying Advantages

• Small quantities of wet or damp materials
• Remain in repository
• Item by item inspection
• Best results for plastic coated materials

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Air Drying Disadvantages

• Labor intensive
• layout and reassemble records
• plastic enclosures must be removed
• Large areas of surface space required
• Cockling without restraint during drying results
  in increased volume of dried materials
• Coated papers block without interleaving
• Extensive handling may increase.damage

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Air Drying Disadvantages

• Costs for supplies and equipment
• absorbent materials
• energy to operate dehumidifiers and fans
• Costs for staff time
• Staff not carrying out regular work routine
• Workspace occupied by drying activities
• Chance for disruption of original order
• Possibility of mold

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Dehumidification Drying Advantages

• Suitable for large quantities of damp materials
• Can be carried out on-site or at vendors
  facility
• Allows for access for the materials during the
  drying process

Dehumidification Drying Disadvantages

• Results in greatest distortion
• Corrosion of metal fasteners

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Vacuum Freeze-Drying Advantages

• Large quantities of wet materials.
• Least distortion
• Minimizes corrosion of metal fasteners
• Soluble media will not move
• Coated papers do not require interleaving
• Plastic films do not require removal.
• Less chance for disruption of original order.

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Vacuum Freeze-Drying Disadvantages

• No access
• Must be frozen prior to drying
• Small quantities expensive
• Bubbling of cellulose nitrate coated
  architectural linen drawings

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DORIS HAMBURG, DIRECTOR PRESERVATION PROGRAMS
MARY LYNN RITZENTHALER, CHIEF DOCUMENT
CONSERVATION LABORATORY
CATHERINE NICHOLSON, SUPERVISORY
CONSEVATOR DOCUMENT CONSERVATION LABORATORY
STAFF FROM THE
WASHINGTON NATIONAL RECORDS CENTER
DOCUMENT CONSERVATION LABORATORY RESEARCH AND
TESTING
ACKNOWLEDGEMENTS
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