as lichens, that have simply been placed in labeled packets and stored in small drawers or boxes.
• Specimens and mounting sheets may have been treated with toxic chemicals such as mercuric chloride to make them resistant to mold and pests. Mercury-treated specimens will off-gas mercury vapor continuously over time and may have gray-black stains that are often mistaken for mold.
• Herbarium sheets and packets dating from about 1840 to the early 20th century may have been made of very acidic papers and can be extremely fragile when damp or wet.
• Adhesives used to mount plants or attach labels and fragment packets may soften or dissolve when exposed to moisture or high humidity.
Common Types of Damage
• Immersion in water may result in degradation of the mounting sheets or paperboard boxes that house specimens.
• Past treatment with mercuric chloride makes paper sheets brittle; exposure to water increases their fragility.
• Specimens housed in boxes are sometimes enclosed in ziplock plastic bags, which can protect them from water or moisture but may melt in a fire.
• Inks may run when wet, affecting legibility.
• Water or moisture can soften or dissolve adhesives. When this occurs:
+ specimens may become dissociated from sheets and data
+ paper packets containing specimen fragments may become dissociated from sheets
+ data labels may become detached, destroying the specimens’ scientific value
Supplies
What You May Need and Why
• Camera
• Pencils and paper for keeping records
• Protective gloves (nitrile, vinyl, or neoprene)
• Safety gear, including a respirator, if mold or contamination is present
• Silicone-release paper/film, waxed paper, or freezer paper, to protect specimens
• Bubble wrap or polyethylene foam for packing
• Sturdy boxes
If Specimens Are Wet
• Plant presses, or plant dryers, for drying specimens
• Fans and dehumidifiers
• Polyethylene sheeting for freeze-drying and packing
If Specimens Are Damaged But Dry
• Respirators
• Vacuum with HEPA filter
Triage
How to Decide What to Treat First
• Salvage type specimens (those referred to in the first published account of a new taxonomic category) first, no matter what their condition.
• Give next priority to rare, endangered, or extinct species.
• Treat wet items before dry.
What to Do
• Keep records—of conditions at the time of the emergency, and of your actions and when you take them. Use both words (a diary or log) and photographs. This information may be vital in discussions with an insurance company or lender, or to document when damage occurred (e.g., in the disaster vs. during handling).
• Keep identifiers (labels, box or shelf numbers, etc.) with specimens. If necessary, transcribe identifying information onto clean paper kept with the specimens.
Wet Specimens
• Damage is time sensitive. Act quickly.
• Keep labels with specimens.
• Do not rinse specimens.
• Avoid direct handling. If you must move specimens, do so on some sort of rigid supports or in original folders or boxes.
• Always wear protective gloves when handling specimen sheets or boxes.
Drying Specimens in Place
• If possible, dry specimens where they are. This dramatically reduces potential for mold, pest infestations, and mechanical damage from moving them. Use dehumidifiers and fans to dry and circulate the air, or arrange for an emergency-response company to provide equipment for replacing moist air with dry.
• If specimens are in well-sealed metal cabinets and have not been immersed, keep the cabinets closed during drying. Otherwise, open the cabinets.
Air-Drying Outside of Cabinets
• When in-cabinet drying is not feasible, remove boxes and folders containing specimens from the cabinets and place them on tables.
• Open boxes. Remove and discard wet folders.
• Use fans directed over rather than at the specimens to help keep air moving.
• If mold becomes visible on any specimen, immediately cease the use of ventilation fans and remove the infected specimen(s) to the outdoors.
• Place groups of specimen sheets in plant presses to help reduce distortion during the drying process. To keep them from sticking together (especially since softened adhesives may become exposed when specimens are moved), separate the sheets from one another with silicone-release paper/film, waxed paper, or freezer paper. Make pinhole perforations in the separating sheets to facilitate drying.
Freezing and Vacuum Freeze-Drying
• If specimens will become mold-infested before they can be air-dried, they may be frozen, though the process will likely cause some mechanical damage.
• Stack specimen sheets, separating them with silicone-release paper/film, waxed paper, or freezer paper. Double wrap the stacks in well-sealed polyethylene sheeting.
• Specimens in boxes should be kept in those boxes to avoid loss of data that may be recorded on them.
• Freeze at or below 32°F/0°C until arrangements can be made to vacuum freeze-dry the specimens (the polyethylene sheeting will be removed during freeze-drying).
Drying with Heat
• Use low heat (no higher than about 100°F/37°C) to dry herbarium specimens. However, if specimens have been treated with mercury salts, subsequent heat treatment will increase the rate of mercury off-gassing, so drying ovens should be connected to a fume cabinet or similar safe outlet for vapor.
Subsequent Cleaning
• Once specimens and sheets are dry, removal of contaminants should be attempted only by experts.
Dry Specimens
