top of page
ホーム: ようこそ!

Deacidification treatment

Neutralization of acid paper

Valuable materials

To the next generation

Simple repair

Document repair and binding

Improvement of condition

Expansion of use


Improvement of storage environment

Better storage

Safe exhibition









* Former company name "Preservation Technologies Japan Co., Ltd."

The new company name has been changed to "Kihara Preservation Co., Ltd."

Paper is made up of many fibers and has moderate suppleness and toughness. However, acid paper, which began mass production in the middle of the 19th century (in Japan in the latter half of the 20s of the Meiji era), decomposes its fibers due to the acidic components and in some cases deteriorates to crush. Acid paper is printing paper such as books, magazines and newspapers, and writing paper such as straw paper. Paper in the Taisho era, especially before and after the war, is extremely fragile.

Deacidification is a technology that neutralizes the acidity of acid paper and has the effect of extending the life of the paper three to five times. Our bookkeeper deacidification process contributes to the long-term preservation of irreplaceable physical materials.

Deterioration of acid paper is invisible because it is a chemical reaction, but it progresses slowly and constantly. Efforts to leave as many books and documents as possible in the collection of libraries, archives, and museums to the next generation are nothing but the work of transmitting unbiased information to the future.

Our efforts


Preliminary inspection work will be carried out to determine whether the material requires deacidification and to confirm the need for repair.

In the bookkeeper deacidification process, the deacidifying agent spreads to every corner of the page in the processing layer filled with the processing solution.


Simple repair


We propose repairs that enhance usability, such as repairing tears and rebinding.

What is acid paper in the first place? What is a bookkeeper?


What is acid paper?

Paper is made of plant fibers and has moderate suppleness and toughness. However, in acidic Western paper such as printing paper, newspaper paper, and writing paper, which are made of wood parve and mixed with aluminum sulfate (rosin-sized fixing agent) in the papermaking process, the cellulose that makes up the fibers is hydrolyzed by acidification. It breaks down, loses its flexibility, and in some cases deteriorates until crushed.


What is a bookkeeper?

Bookkeeper deacidification treatment provided by our company is one of the material preservation that neutralizes the acid of acid paper and realizes long-term preservation of paper materials, and Preservation Technologies LP (PTLP) located in Pittsburgh, USA Developed by Bookkeepers can safely deacidify books, manuscripts, maps, sheet music, pamphlets, newspapers and more, extending the life of physical materials over a long period of time. The basic process of this technology is to receive materials from libraries, archives, museums, etc., deacidify them at the Saitama factory, and then return them.

bottom of page