Tips on Freeze Drying

And a product review of the Taxi-Dry system

By Ralph Garland

Freeze-drying has been around for a long time, basically since refrigerators and freezers were first used. Not so, you say? Well, what about the items that have become freezer-burned while stored in a freezer? Freeze-drying and freezer-burn are similar. Freeze-drying is the intentional removal of moisture from an object using a vacuum process. Freezer-burn is the unintentional removal of moisture from an item while it is frozen.

I’m not a scientific person, and basically, I don’t care how a process works or why it works, as long as it works. I have found that attention to basics, sound logic and proper preparation effort will help greatly in the freeze-dry process. My tolerance level and my patience is questionable at best, and I have learned that for the best results, the freeze-dry process should not be hurried.

Freeze-drying will never take the place of conventional taxidermy, but it can be used as a tool or an asset to most taxidermy businesses. The cost of a unit can be prohibitive to many taxidermists, but by subcontracting their services to others, they can overcome the deficit. Personally, I try to keep freeze-dry specimens on the small side. Sure, you can freeze-dry larger items, but if you keep the projects small and the poses simple, it is much faster, hence more profitable. Normal freeze-dried items are turkey heads, crustaceans, deer feet, reptiles, amphibians, and small birds, fish and animals.

We have had freeze-dry capabilities at Piedmont Community College, where I teach taxidermy, since 1985. Our students have access to a wide variety of freeze-dry specimens. It is not unusual to see a combination of deer feet, deer noses (for reference), birds, snakes, frogs, lizards, turtles, scorpions, etc., in our large machine, all at the same time. Because of this mixture of specimens, we normally run the specimen chamber of our large machine at a temperature setting of 10-degrees below zero. This is done to prevent distortion and shrinkage to certain specimens. I have found the colder the temperature, the less distortion, but the time it takes to dry the specimen is much longer. Because of the wide variety of items in the large machine, we keep the specimen chamber temperature the same year-round. Slowly raising the temperature setting in the specimen chamber during the drying process speeds up the drying time. Some items can be freeze-dried faster than others, but raising the temperature of the specimen chamber when different types of specimens are in the chamber can cause some specimens to distort in shape. This is especially true for fish and lizards.

Like most things in taxidermy, freeze-dry machines and freeze-dry technology has improved as it has evolved. The Taxi-Dry machine produced by Freeze-Dry Specialties, Inc., headed by Alan Anger, has a small unit available that is financially within the reach of many of taxidermists today. Not only is the unit within the financial means of more people, the technology that goes into the newer machines has improved the product also. Small machines today will dry items faster. The smaller chamber allows for the increase in specimen chamber temperatures, which allows for faster process.  Even with the increase in technology and speed, it is still important for taxidermists to properly prepare specimens, or pay the price by having distorted specimens.

The Taxi-Dry machine we have will dry any item you can fit into the chamber. However, it is best to put items of the same family in the machine together. In other words, load the machine with groups of deer feet, quail, turkey heads or small panfish. By loading the chamber with the same type of specimens, you can slowly raise the temperature of the chamber without as much chance of distorting the items. Another reason for drying the same type of specimens together is to compare the results of each item. By comparing items, you can determine how shot holes can affect a turkey head, or you can compare a well-prepared head to one that was somewhat freezer-burned. You can also check different injection formulas and compare the results to determine which one works best.

Always remember—a chamber loaded with a mixed bag of critters has to be run with a colder setting to prevent distortion. This is because different items release moisture (dry out) faster than others. Quail, doves, parakeets, etc., will dry faster than snakes. Snakes were created in such a way that their skins do not allow moisture to escape easily, nor allow moisture to penetrate easily. I have found that the drying process can be speeded up by using an insect pin and pricking tiny holes in the specimens. I feel it is best to wait at least a week to do this after the drying process has started. Be sure to watch where you prick the holes because you don’t want them to show.

A trick I learned from Alan Anger was to spray a mist of water over small fish right before you put them in a freezer. I have no idea what it does or why it works, unless the thin layer of ice acts as a protective shield before it is placed in the freeze-dry chamber. I have found that I don’t have as much shrinkage and distortion with fish when I do this. Whether it is fish or other types of specimens, it is vital to plump up any areas that have lost their fullness and restore them to their original sizes and shapes. Items that have become freezer-burned do not freeze-dry as well as fresh specimens do. Always keep this fact in the back of your mind, particularly if you do work for other taxidermists.

Freeze-dry machines are not magic; you will get back what you put into the machine or maybe even worse. If you prepare and pose a specimen correctly from start to finish, you will be pleased with the results. If you half-heartedly go through the motions you will, most certainly, have a specimen that shrinks and distorts so badly that it will be basically useless. There is more to the process than most people normally think. Because I teach taxidermy, I am well aware of all the mistakes and shortcuts people make. Anything worth doing is worth doing right.

The Taxi-Dry machine I mentioned earlier is a neat unit. It is very quiet when running, and to an old grouch like me, that is a definite plus. I’m not very mechanically inclined, but I find it very easy to change the oil and remove the ice block. The machine is constructed in such a way that it makes the process and operation very easy. If a “mechanically challenged” individual like me can catch on to the operation of the machine, anyone can use it. (I usually let Sandy, my wife, do all the mechanical stuff, just to be on the safe side.)

I was eager to test the Taxi-Dry machine to see if it would live up to its billing. I was told it would dry turkey heads, small fish, quail, etc., in seven days. To say the least, I was very skeptical about this seven-day claim. It just sounded too good to be true. For my first test, I decided to dry a mixed bag of items. My thinking was that by deliberately trying different items together and slowly raising the chamber temperature, distortion and shrinkage would most likely happen. I prepped and posed a bluegill, a water moccasin, and a bantam hen (banty is the common name used by many people). The bluegill was a little bigger than the size I normally feel comfortable to freeze-dry; but after all, this was a test. I also felt the banty hen was a tad on the large size, but I posed it in a sitting position and it went into the chamber easily. The cottonmouth moccasin was a small one, only about 20 inches long, but knowing how long it takes reptiles to dry, I felt it would be just what I needed.

I have a rule I usually go by when freeze-drying items, and it can save you a lot of frustration if you go by it: keep it simple. It saves a lot of posing time and the specimens also take up less space in the chamber. I placed the three items in the chamber and awaited the results. The temperature setting was as low as it would go, and after two days I raised it a bit. The next day, I raised it again, and on and on until the storage unit was at room temperature. Every day I would look at the items to see if they were holding their shapes. I could not see any distortion or shrinkage through the chamber, but I still had doubts. Thinking “better safe than sorry,” I left the three items in the chamber for 11 days. Afterward, the unit was turned off and the chamber opened. I was definitely pleased with the results. There was no distortion or shrinkage and the items were completely dry!

Could they have been dry in seven days? Maybe, maybe not. I was satisfied with the 11-day time period, so why worry. Knowing that larger items take longer to dry, and compared to the time element I was accustomed to, I was happy. The fact that there were no anatomical changes was what really surprised me the most.

I thought it was time for something a bit larger, so an aoudad fawn was placed in the chamber. Again, I followed the same process I had used before. I checked the eyelids, nose, lips, and ears every day, looking for signs of trouble. With fawns, these areas will shift and move during the drying process. I had injected a little water into the nose to restore the plumpness. I also injected the lips just a bit to keep their fullness. As I daily checked the specimen, I was elated that everything stayed as it should.

I was now convinced that the Taxi-Dry machine would do what I had been told it would do. The machine will do its part, but taxidermists must do their part also by using proper preparation procedures. No shortcuts—do it right. After all, it’s your reputation.

 

Ralph Garland is the taxidermy instructor at Piedmont Community College in Roxboro, North Carolina.

 

Ralph Garland checks an opossum in the freeze-dry chamber. Mammals of this size are normally mounted by conventional taxidermy, but this offered an additional test. The opossum dried in 28 days.

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