Gentle Deacidification with the ZFB||2 Process

Deep penetrating deacidification and gentle treatment

The deacidification of paper is a preventative measure which prevents further deterioration of the paper. The earlier the paper is deacidified the better! If the cellulose structure of the paper has been severely damaged or even destroyed by acid, the deacidification treatment will come too late. Therefore, it is absolutely necessary to act promptly.

The ZFBII2 process is a non-aqueous liquid process to deacidify bound and unbound paper objects. The mild deacidifying liquid penetrates deeply into the core of the paper and deacidifies it accordance with the guidelines issued by the DIN recommen- dations provided by the committee for standards in libraries and documentation.*


How does our ZFBII2 process work? 

The ZFBII2 deacidifies paper using a mild dispersion of magnesium oxide (MgO) and calcium carbonate (CaCO3). These two substances form the deacidification agent. The vehicle is non-polar solvent heptane. During the treatment process, the deacidifying agent penetrates deep into the paper and neutralizes the acid. Subsequently, the solvent is vacuumed off.

The pH-value of the paper is thus raised into the alkali pH-value range between 7.0 and 9.5. Furthermore, a surplus of the deacidfying agent is introduced into the paper, forming a so-called alkali reserve. The alkali reserve buffers the paper against damaging environmental influences in the future.

Before beginning the deacidifying treatment, all of the objects are carefully pre-sorted by our employees in order to ensure that only those objects are deacidfied which actually require this treatment. Afterwards, the objects are sorted into stainless steel baskets, which are then placed into the ZFBII2 treatment chamber.

Subsequently, the treatment chamber is flooded. The deacidfying agent penetrates deep into the paper. Afterwards, the treatment liquid is drained off and the objects are dried by completely removing the solvent using vacuum pressure.

Finally, the books, files and bound volumes of newspapers are inspected again by our quality control process.


How effective is the ZFBII2 process?

Deacidification into the deepest core of the paper! Using SEM/EDX analysis** we have proven that the ZFBII2 process deacidifies the paper to its core. By combining these two methods of analysis we can create space-resolved element-distribution images.

Since the ZFBII2 process is a liquid dispersion method – meaning that tiny particles of the deacidifying agents float within the treatment liquid – the proof of deep penetration using this method is very important to us!

A successful deacidification requires deep penetration of the deacidifying agent into the core of the paper. This is the only way to ensure that the paper will be protected in the long run.

With this analysis verification we go one step further in our quality demonstration record than that which is required by the DIN standards recommendations*. Evidence of deep penetration to the core via SEM/EDX analysis does not yet form a part of the DIN recommendations.

The figure illustrates the deep penetration of the ZFBII2 deacidification. Even distribution of the deacidifying agent can clearly been seen throughout the entire paper core. The intense turquoise colour illustrates the portion of the deacidifying agent. Therefore, the deterioration of the paper has not only been stopped on the surface, but within the deepest part of the paper core.


The cut edge of a piece of paper which has not been deacidified. The red frames mark each of the cut edges.

The cut edge of a piece of paper which has not been deacidified. The red frames mark each of the cut edges.

The homogeneous distribution of the deacidifying agent after ZFBII2 treatment over the cut edge of the sheet proves the deep penetration of the agent into the paper.

The homogeneous distribution of the deacidifying agent after ZFBII2 treatment over the cut edge of the sheet proves the deep penetration of the agent into the paper.

The advantages at a glance

  • Mild deacidification. The paper is neutralized evenly deep into its core.  The pH-value is raised to between 7.0 and 9.5 and an alkali reserve is introduced into the paper. 
  • Increases the useful life of the paper. The ZFBII2 process increases the useful life of the paper by a factor of 4 or 5 times.  
  • Comprehensive restoration assistance. ZFB offers stock preservation services from one source. We ensure that certified conservators supervise all processes. Should additional restoration work on your objects be desired or necessary, we offer all conservation at one location and from one source. We not only perform deacidification work but are conservators first and foremost!
  • Cleaning at no extra cost. During the preparation work for the deacidification process, all of your objects are cleaned by our staff. Any dust layers or light soiling is removed for you at no extra cost. In the case of more severe mould attacks, we will be pleased to advise you and can make an offer to remove the mould – a service that we provide as well.
  • Suitable for bound and unbound archive and library stock. The ZFBII2 process deacidifies bound as well as unbound papers. Foliation of the objects is not necessary.
  • Stabilisation. The ZFBII2 has a slightly stabilising effect on the paper.

  • There are practically no side effects or visible signs of treatment. At least 98 % of the objects exhibit no visible signs of the treatment. Undesired side effects such as bleeding from stamps, grease sticks or indelible pencil markings arise only very rarely.
  • No mechanical strain on the paper.The objects are not fanned open or clamped on the spine of the book. Therefore, damage due to mechanical strain can be avoided. 
  • No increase of volume. In contrast to aqueous deacidification methods, there is no increase of volume by 5% - 10% using the ZFBII2 process. Valuable shelf space in archives and libraries can thus be saved and no paper-damaging compressing will be required.
  • Fast processing time. Less than four weeks from incoming delivery to dispatch.
  • Reasonable price. The ZFBII2 process is less expensive than conventional mass deacidification processes. We would be pleased to make you an individual offer based on the amount of stock to be deacidified.
  • Deacidification in accordance with DIN recommendations*. The deacidification is carried out in accordance with the guidelines provided by the DIN recommendations of the standards committee for libraries and documentation created by Rainer Hofmann and Hans-Jörg Wiesner.

Regarding the treatment of aged papers

Explanation of aging mechanisms, the deacidification process and current knowledge regarding the alkali reserve which is introduced into the objects.

At this point, we would like to provide more transparency regarding the complex topic of mass deacidification and its quality parameters. More information on this topic can be found here.

* DIN-recommendation: Bestandserhaltung in Archiven und Bibliotheken, Hofmann, Rainer/Wiesner, Hans-Jörg, Beuth-Verlag.

** SEM: Scanning Electron Microscopy