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Preserved Specimens FAQs

How do you obtain your specimens?
Specimens are acquired from suppliers worldwide.

Is the acquisition of specimens regulated?
The US Fish and Wildlife Service and the US Department of Agriculture both monitor the trade in biological specimens. USF&W oversees the import and export of specimen materials. The USDA monitors and regulates the use of domestic animals, in whole and in part, used as preserved material.

How can I be sure you are in compliance with regulations?
We are subject to unannounced inspections by USDA personnel, and we are required to file annually to renew our USDA license. US Fish and Wildlife regulations require documentation for all specimen imports and exports, including microscope slides.

What about cats?
Cats are sourced from pounds and shelters. All shelters are required to retain animals for a specified time to maximize the possibility of adoption. Animals that are not adopted are euthanized at the shelters and preserved for dissection under the guidance of USDA regulations. These animals are "recycled" for education; otherwise they would have been incinerated or placed in a landfill after euthanasia.

What about fetal pigs?
Fetal pigs are a by-product of the pork industry. The fetal pigs are taken from sows after they have been killed at the packing plant. Fetal pigs are not raised specifically for dissection; they would be far too expensive.

What about sharks?
The harvesting of dogfish sharks is regulated by National Marine Fisheries to protect the species. Quantities used by our industry are very small in relation to the overall harvest.

What about sheep brains? Are they scrapie-free?

It has not been scientifically established that scrapie can be transmitted from sheep to humans via consumption of scrapie-infected sheep, much less via contact with a classroom dissection. Nonetheless, children’s safety is the highest priority for us. That’s why we use extra precaution to ensure sheep brains we obtain are scrapie-free. Our vendor of sheep brains takes part in the USDA's Scrapie Free Flock Certification Program (SFCP), designed to demonstrate scrapie-free flocks through vigilant surveillance and testing—both of sheep heads and live sheep.

What is the difference between "fixation" and "preservation"?
Fixation involves the chemical alteration of protein to prevent breakdown. Dilute formalin solutions are most effective as fixatives. Preservation is the process of maintaining the state of fixation. Formalin-free "holding solutions" like WardSafe are good for preservation.

How are your specimens preserved?
We offer a wide variety of preservation types; "standard" dilute formalin fixation, alcohol preservation, freeze-drying, and formalin-free fixation. Larger vertebrates are embalmed with a formalin-phenol-glycol embalming fluid.

How does embalming work?
The preservative is injected directly into the specimen's arterial system. It perfuses all tissues and insures complete preservation.

How are smaller specimens preserved?
Most are preserved by immersion directly into the preserving fluid. Most specimens are relaxed or anesthetized before immersion.

What are freeze-dried specimens?
Freeze-drying is the process of removing all the water from the specimen, at the cellular level. This is done under extreme low temperatures in a vacuum (an elaboration of "freezer burn" that occurs in long-term frozen storage). Specimens are thus preserved without the use of any chemicals. Freeze-dried specimens can be rehydrated in a dilute alcohol solution.

How long will freeze-dried specimens last?
Again, indefinitely in the freeze-dried state (though conditions of high humidity must be avoided). Once rehydrated in alcohol, they should be used within a week or ten days.

Are your specimens safe to use?
Yes, every preservation method yields specimens that are safe for your students to use, provided that standard lab safety practices (hand and eye protection) are used.

How can I be sure? Isn't formaldehyde dangerous?
Formalin (formaldehyde gas dissolved in water) is the most widely used, economical, and effective preservative. Used in low concentration (5%) it effectively preserves the entire specimen and prevents decay. Specimens so fixed are rinsed and packed in bags or pails with WardSafe, our proprietary formalin-free holding solution. The amount of residual formalin remaining is usually less than 1%. The federal OSHA standard for formaldehyde exposure is 0.75 ppm over an 8 hour period.

What is WardSafe?
WardSafe is our proprietary holding fluid for preserved specimens. Independent laboratory tests have determined that WardSafe is not a skin sensitizer or a skin or eye irritant.

What are formaldehyde-free specimens and how are they preserved?
Specimens are chemically fixed without formaldehyde. The formula is proprietary but as with all of our products, an MSDS accompanies each order. Specimens have the same shelf life as standard formalin fixed material, although they appear slightly darker, otherwise they are similar.

What about specimens, like sheep hearts, that I can acquire fresh or frozen from meat packers?
Dissecting "fresh" material is not nearly as safe as working with preserved material, due to a real danger from pathogenic microbes that can contaminate such material.

What does latex injection do?
The injections are done to more clearly show the elements of the circulatory system. Red latex traditionally delineates the arteries, blue the systemic veins, and yellow the vessels of the hepatic portal system.

What are "singles, doubles, and triples"?
A "single" is an injection done with red latex, only, in the arterial system. A "double" has a blue injection added to delineate the systemic veins. A "triple" has yellow latex injected to show the hepatic portal system (veins of the digestive tract) in addition to the other two.

My specimen (dogfish, rat, cat, or rabbit) has a stitched or stapled incision in the abdomen. Why is that?
Triple injections require exposure of internal vessels that are the injection points. A small incision is made for this purpose.

How long will my specimens last?
Indefinitely, if kept in pails in WardSafe as received. Specimens packed in bags will last a year or more. Once opened and worked on, specimens should be returned to the pail or bag to keep them in good condition for the next lab period.

What can I do if mold develops?
There are inhibitors in our preservatives that will prevent or inhibit mold growth, but under some conditions mold growth may occur. The possibility can be minimized by following the directions for the previous question. If mold does develop, use our Preserved Specimen Conditioning Fluid (39 V 1697) for control, or spray or immerse in a 70% alcohol solution.

What can I do to prevent my specimens from drying out?
Specimens can be returned to their containers for storage over a semester break. Simply covering the specimen with paper towels dampened with the packing fluid will keep them fresh and moist for several days.

My specimens were dried up when I got them. What can I do?
Were the specimens ordered as freeze-dried material? Rehydration will occur by following directions and immersing in 10% methanol. If they were originally liquid preserved and have dried in the bag, we will replace.

What packaging option is best?
Pails and bags each have advantages so you can choose that which best suits your teaching needs:


  • Best for long term storage
  • Container and fluid useful for storage over long-term work
  • Can be tightly resealed for storage
  • Container has other uses


  • Increased weight
  • Take up more space
  • May require special tool to open


  • Minimal fluid in bag
  • Easy to dispense to students
  • Less weight is more economical to ship
  • Can be used for temporary storage of specimens being worked on


  • Shelf life about 1 year
  • Bags discarded after use
  • Specimen drying more likely to occur

How are your products labelled?
Completely. The specimen type, quantity, and catalog number are boldly indicated on our pre-printed package labels. We also include the preservative formula and basic "use and care" instructions on our labels. It is the most complete labelling in the industry. We also include MSDS for original fixatives and our holding fluids with each order.

I have a problem. How do you handle it to my satisfaction?
Our labels include a lot code, a series of numbers printed in the top panel of the label. These numbers enable us to track the product history. Describe your problem and indicate the lot code in your communication to us. We will resolve the problem to your complete satisfaction.

How should my students handle specimens?
Students should wear hand and eye protection along with a lab apron.

How do I dispose of my specimens when labwork is completed?
You should check with your state and local authorities to insure proper disposal. In most instances, specimens can be disposed of as ordinary household waste, and may either be placed in a landfill or incinerated.

Can I use this fluid to preserve other specimens?
WardSafe is a holding fluid - not a fixative. It cannot be used to preserve fresh material, but it can be used for safe storage of specimens that are already fixed.

I have special needs for items not in your catalog. Can you help?
Give us a call. We do custom packing and frequently prepare special sets for our customers.

How are your insects and smaller invertebrates preserved?
Many invertebrates are preserved in 70% alcohol. Larger forms like starfish and clams are formalin fixed. All are packed in WardSafe when shipped in pails. Insects are packed in a modified WardSafe solution containing a higher percentage of alcohol.

How are your plants preserved?
Plants are preserved in various botanical fixatives (usually FAA or FAA evergreen fluid). They are packed in a 50% glycerine solution, which retains color and flexibility. Like other preserved material, they will last indefinitely.

I am pregnant, are preserved specimens safe to use?
We recommend you speak to your primary care physician

How are Museum Mounts preserved?
Museum mounts are expertly dissected and displayed preserved in 3% formalin. They are encased in acrylic.

My museum mount has lost some fluid, what should I do?
If there is no damage to the acrylic container you may refill the museum mount yourself using 3% formalin solution. Alternatively, you can contact our customer service department and ask about museum mount repairs.