Cleaning and Restoration Magazine
The Official Publication of ASCR International
Thanks to recent technological breakthroughs, the freeze-drying recovery method is uniquely positioned to set a higher standard of quality in the restoration industry. Freeze-drying is a practical, effective and affordable way to restore the water-damaged contents of homes and businesses devastated by floods or other disasters.
comes of age
The actual freeze-drying process was first tested and used in 1890 in Leipzig, Germany. During World War II, the U.S. government used freeze-drying as a means to store human plasma. In the 1950s, the freeze-drying process began to be routinely used in the food and drug industries. It wasn't until the 1970s, however, that conservators around the world began using freeze-drying as a method of recovering water-damaged books and documents.
The widespread use of freeze-drying technology today is a testament to both its versatility and effectiveness. The process is particularly useful to water restoration companies, scientists, museums, insurance companies, pharmaceutical manufacturers, food producers, florists and taxidermists.
Here's how it
First, the object to be freeze-dried is frozen solid to lock the structural form firmly into place. The object will maintain its pre-frozen shape throughout the entire process.
Second, the object is placed in the freeze-drying chamber and a vacuum is established, which ensures that the chamber is devoid of air and operating at a very low absolute pressure. During the freeze-drying process, the drying equipment mechanically creates a negative pressure lower than that found in outer space! When the inside of the drying chamber reaches the proper pressure and temperature, the moisture in the frozen object is converted to vapor.
Third, a condensing surface outside the chamber, which is typically colder than -40 degrees Centigrade, attracts the vapor coming off the frozen object and turns the vapor back to ice. This also protects the high-grade vacuum pump from water, oils and fats that might be part of the composition of the object being dried.
Fourth, a controlled gradual temperature rise completes the process by driving off more vapors and promoting the release of bound water from the product. Ninety percent of the drying is done at temperatures below freezing.
Freeze-drying has a number of significant advantages over vacuum-drying. First and most importantly, freezing the water-damaged item immediately stabilizes it, allowing it to be stored indefinitely before it's dried. The water in the item remains frozen while the freeze-drying process converts it to a gaseous state.
Vacuum-drying, on the other hand, which changes a liquid to a vapor, can result in a much greater risk of expansion, distortion, sticking and staining. Vacuum-drying can also allow an item to incur additional damage because the drying cycle can take several weeks. During this time, the water in the item remains in a liquid state until it evaporates, which permits inks and other materials to continue to migrate.
Although freeze-drying generally costs 10 to 25 percent more than vacuum-drying, many scientists, conservators and water restoration experts feel that freeze-drying's superior results are worth the slightly higher cost, particularly when trying to restore more valuable items, as well as more challenging ones such as coated papers.
A boon to water
If given a choice, most homeowners would undoubtedly choose to rescue the contents of their home rather than the home itself. Items such as family bibles, photo albums, personal letters, scrapbooks, yearbooks, collectibles and childhood mementos have great sentimental value and are simple irreplaceable. People have their very identity wrapped up in these items and desperately want them back in whatever shape they can get them in.
Typically, insurance companies pay out very little for items of sentimental value, but they should do whatever is necessary to recover and restore such items to the best condition possible.
Water and fire, directly or indirectly, have always been the primary enemies of books, important documents, keepsakes, stamp collections, baseball cards, and other items of collectible or sentimental value. Oftentimes, the water used to extinguish a fire can wreak greater destruction than the fire itself. This is also true for businesses, which often have many important, mission-critical documents of great value on their premises.
Of course, there are many other sources of water that constitute a potential hazard to the items listed above. Nature is responsible for tornadoes, hurricanes, floods, rainstorms, freezing water and snow, while man has contributed leaks in drainage in steam pipes, the breakdown of water heaters and air conditioning systems, clogged sinks and toilets, leakage of water tanks, roofs and windows, seepage in basements, clogged roof gutters and downspouts, and broken water mains, to name a few.
However, there's another enemy of water-soaked items that is often overlooked because, until freeze-drying became as convenient and affordable as it is now, nothing could be done about it. This villain is time. The problems associated with water damageabsorption and swelling, mold infection, migration of inks and dyesall grow worse with the passage of time. The more time that passes, the more complicated, expensive and time-consuming it is to salvage an item.
Stabilizing an item by freezing it as soon as possible after it's been damaged, dramatically increases the odds that it will be able to be salvaged satisfactorily. Simply placing a water-damaged item in a freezer is an important first step in the freeze-drying process.
Freezing an item halts the reproduction and development of mold spores and stabilizes the water-soluble inks, dyes and colorants used in items such as manuscripts, maps, sketches, drawings and the like. Stabilizing a water-damaged item by freezing it also provides the opportunity to calmly assess damage and determine what repairs or restoration might be required.
Paul H. Storch of the Minnesota Historical Society in St. Paul, is widely regarded as one of the leading object conservators in the country. He had this to say about the freeze-drying process:
"We've had an Ultra Dry Plus unit from Freezedry Specialties for about a year now. I had been pushing for a vacuum freeze-dryer since I came here nine years ago. Luckily, we haven't had any disasters come up so we haven't had occasion to use it on documents, but that was certainly one of the reasons we got it. We have a new department head who's in the book and paper field, and she was very excited to get it."
"I've used it for three-dimensional organic objects like waterlogged wood and leather, and it has worked quite well. I just freeze-dried some fragments of late-19th century European softwood coffins that had metal handles attached. There was a stark contrast between the air-dried, untreated fragments and the freeze-dried items. The freeze-dried fragments were much more natural looking, with negligible shrinkage and distortion.
The dawning of
a new era
One of the advisors at the Dri-Eaz training center is Terry Smith, Vice President of Water Removal Technologies, Inc., a newly formed division of Freezedry Specialties, Inc. This new division was spun off to deliver exciting exciting new products to the water removal industry that focus exclusively on the restoration of contents rather than the structure itself.
Smith is known for his many inventions in the restoration industry, including Skidders furniture movers, Florguards floor protectors for vinyl and hardwood floors, and the Scuff Shield hard surface temporary floor protector for the appliance industry. He also holds additional patents for water removal technologies, including a structural drying system for drying interior cavities of structures and a hardwood floor drying system which dries hardwood floors from the bottom side.
Smith and I have several patents pending for applications dedicated to the water restoration industry, including a method for pressing wrinkled documents and books back to a flat condition after they've been dried. Another patent application is for deodorizing water-damaged or smoke-damaged items during the freeze-drying process that will enable restoration companies to offer even greater value to their customers.
Here's how Smith explains the process; "This type of deodorizing is very new to our industry. Any porous item, such as paper, clothing or tapestry, can absorb odors. Using a freeze-drying vacuum chamber, we create a perfect vacuum and remove all of the air from the item. We then add deodorized air back into the chamber for the pores in the item to absorb. After only an hour in the chamber, the item is completely deodorized at a cellular level."
This exciting new technology can deliver results that need to be experienced to be believed. For example, a valuable Beanie Baby damaged by sewer water can be washed out with a disinfectant, frozen and dried in a vacuum chamber. After it's dried, a deodorizer can be added to restore the item to its original state. Results like this were unattainable until now. Technology is improving the restorer's arsenal of equipment for fighting disasters, and freeze-drying is becoming one of the most practical, effective and affordable solutions for the restoration of water-damaged items.
Alan Anger, founder and president of Freezedry Specialties, has more than 30 years of experience in the freeze-drying industry. He has worked and consulted for a wide range of pharmaceutical and biotechnical firms, food-processing and disaster recovery companies, museums and scientific organizations.