Volume 2, Number 4
Oct 1989

Lithco Develops Deacidification/Strengthening Process

Lithium Corporation of America (Lithco), a subsidiary of FMC Corporation, has developed a safe, non-toxic proprietary treatment chemical and process for deacidification, buffering, and strengthening of paper that extends the useful life of books and paper documents. Our process is effective, economical, and benign to documents, personnel, and the environment. Ongoing testing on a variety of preservable materials has shown no significant adverse effects.

Background

Lithco has been researching mass preservation technologies since 1987. We have identified a series of compounds which are effective in both deacidifying and strengthening paper in bound books. Patents are pending worldwide. Mw current treatment utilizes a proprietary Lithco product Called -MG-3, a nonpyrophoric magnesium compound which is soluble in both hydrocarbon and halocarbon solvents. No adverse health effects have been seen in the first batteries of dermal, eye, inhalation, and other toxicology tests for M-3 and treated paper.

The Process

Our process is comprised of essentially three steps: Preconditioning (drying), impregnation with active ingredients, and solvent removal. These steps are carried out under mild conditions that are not detrimental to books being treated. During the preconditioning phase, books are equilibrated to a moisture content of approximately 2% by weight. MG-3 does not react as vigorously to moisture as to most current alternatives. Therefore, we do not have to predry to less than 0.5% residual moisture, leaving the books less vulnerable to damage from handling. The proprietary drying technologies that Lithco has developed can reduce the moisture content of paper rapidly in a safe manner prior to neutralizing the acids.

The buffer and strengthening components in MG-3 are deposited at the molecular cellulose level utilizing a halocarbon solvent during the impregnation stage. "Soft" environmentally benign solvents, such as hydro-halocarbons, can and will be used when commercially available. No cosolvents such as methanol are required. MG-3 is designed to interact with the cellulose to strengthen the paper as well as to deacidify and buffer it. Accordingly, naturally aged brittle paper has been treated, and results demonstrate an enhancement in strength. Preliminary results by an independent lab indicated a tenfold increase in the life of treated paper in accelerated aging test and NIT folding studies.

Finally, in the solvent removal stage the excess solution is drained, and the solvent is removed and recovered under vacuum. Books are removed from the unit at ambient temperature. Total processing time is under eight hours.

Future Plans

Currently, we are utilizing a demonstration unit to optimize the process. The capacity of this unit is approximately 20 standard-size books per batch. An optimized pilot unit with the ability to demonstrate all unit operations of the final process will be operational in October 1989. Logistically, we envision that the books will be placed in sealed treatment containers in shelf order. The trays remain closed and locked throughout the process and are returned to the library with the seals intact. A larger pilot unit capable of treating 500 books per day, or 100 thousand books per year, will be operational and available for viewing during early 1990. All of these facilities are located on Lithco's plant property in Bessemer City, North Carolina.

The lack of generally recognized and accepted criteria makes it difficult to evaluate and demonstrate performance of mass deacidification processes, and impedes the selection of a process by preservation personnel. We are endeavoring to help establish industry guidelines and are working closely with preservation administrators and conservators to see that their needs are met.

We are confident that we will be able to produce the same quality of treatment on a commercial scale. While alternative processes may require large scale-ups of unit operations from the pilot to commercial level, the Lithco process requires relatively modest scale-up because of the rapid cycle time.

Our first comercial facility, with the ability to treat one to three million books per year, will be operational in 1991 based an expected commercial demand. Plant location will be based an demand, logistics, and primary customer preference.