Latest measurements in July 2013

CoMa 3 // CoMa 4 // CoMa 5 // C 900
Quality assurance

In our in-house laboratory the results of processing are subjected to constant checks. An extract of results can be found at the top right-hand side of this page.

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Guaranteed quality

Regular checks
Process checks
Long-term measurements

GSK’s conservation processes are carried out according to high quality standards and are subjected to clearly defined internal and external checks. Machines, equipment and chemical mixtures are constantly checked and further developed. The deacidification units undergo maintenance twice a year; the agent solution is constantly checked and renewed. All substances employed are subjected to strict quality controls. Work processes are carried out exactly according to instructions and are fully documented, so that the purpose of all work steps of every individual employee is apparent. GSK constantly invests in research and development on optimising processes and, in the course of its work on the Standards Committee of Information and Documentation (NID), advocates high quality standards.

GSK’s mass deacidification process guarantees long-term deacidification, alkaline buffering and consolidation of the paper. After treatment, we guarantee a pH value between 7.1 and 9.5 after single-sheet deacidification using the Bückeburg conservation process. Only in a few individual cases is the pH value slightly lower, which is often attributable to a particularly dense, closed paper surface. In addition, by using the Bückeburg conservation process an alkaline reserve (calcium carbonate) of between 0.5 to 2 MA.-% MgCO3 as well as an approx. 30% increase in paper stability for 90% of the papers can be achieved. These historical values are based on internal measurements and various studies over the past 14 years, including those by the State Archives of Lower Saxony.

Regular checks

In compliance with the German recommendation "Conservation of holdings in archives and libraries” by Hofmann and Wiesner, regular routine and process checks are carried out on test papers which comply with the standard and have been deacidified using the GSK units in Brauweiler.

Within the framework of so-called "routine checks”, test papers fulfilling the standard are deacidified once a week with all three units and analysed at our in-house laboratory. The pH value in cold extract is tested in accordance with DIN 53124, the alkaline reserve in accordance with ISO 10716 as well as tensile strength after folding.

Process checks are carried out every two years by an independent testing institute. The institute analyses the pH value in cold extract, the alkaline reserve in accordance with ISO 10716, the consistency of deacidification and the tensile strength after folding (Bansa/Hofer method) directly after deacidification as well as after artificial ageing for 24 and 48 days. Artificial ageing simulates the natural ageing process in a standardised, accelerated process by stepwise exposure of the samples to a predetermined increased temperature and increased humidity over a few days in a climatic cabinet.

 

Process Check December 2016

 

Extract pH value

 

Machine

Ageing

Min

Max

Mean

Reference paper I
(untreated) 

 

unaged

4.13

4.1

4.2

 

24 days

4

4

4

 

48 days

4

4

4

Reference paper II
(untreated) 

 

 

 

unaged

4.1

4.1

4.1

24 days

4

4

4

48 days

4

4

4

BCP Reference paper I
(treated) 

 

 

 

unaged

8.7

8.7

8.7

24 days

7.75

7.7

7.8

48 days

9.18

8.9

9.3

BCP Reference paper II
(treated) 

 

 

 

unaged

9.08

9

9.1

24 days

8.63

8.6

8.7

48 days

8.8

8.7

8.9

 

Alkaline reserve

 

Machine

Ageing

Min

Max

Mean

 

 

 

(% Magnesium Carbonate)

 

Reference paper I
(untreated) 

 

 

 

unaged

0.0

0.0

0.0

24 days

0.0

0.0

0.0

48 days

0.0

0.0

0.0

Reference paper II
(untreated) 

 

 

 

unaged

0.0

0.0

0.0

24 days

0.0

0.0

0.0

48 days

0.0

0.0

0.0

BCP Reference paper I
(treated) 

 

 

 

unaged

0.76

0.723

0.803

24 days

0.64

0.602

0.683

48 days

0.62

0.602

0.642

BCP Reference paper II
(treated) 

 

 

 

unaged

0.98

0.883

1.084

24 days

0.7

0.683

0.723

48 days

0,62

0.602

0.642

 

Tensile strength lg after folding

 

Machine

Ageing

Min

Max

Mean

Reference paper I
(untreated)

 

 

 

unaged

15.2

8.6

17

24 days

7.2

3.1

11

48 days

1.7

4.5

0.5

Reference paper II
(untreated) 

 

 

 

unaged

40

35.8

45.1

24 days

6.6

4

8.9

48 days

4.1

1.2

6.9

BCP Reference paper I
(treated) 

 

 

 

unaged

19.3

13.7

24.5

24 days

19.3

13.4

22.5

48 days

13.4

16.8

22.4

BCP Reference paper II
(treated) 

 

 

 

unaged

47.1

39

53.3

24 days

42.6

35.3

49.4

48 days

42.1

29

48.7

 

The measurements show: The stability of untreated acid-containing papers falls much more rapidly in the course of artificial ageing than the stability of papers which were deacidified with the Bückeburg conservation process.

 

Long-term measurements confirm our success

The longer-term effectiveness of our processes is normally only examined by carrying out measurements on artificially aged papers. However, the complex and varying processes of natural ageing, which differ according to storage conditions, can scarcely be comprehensively simulated through artificial ageing. For this reason, it is essential to check the long-term effects of the treatment in the real world. For this purpose in 1995 a repository was set up in which reference papers are stored under authentic archive conditions.

In 2007 the effectiveness of the conservation process was tested by the State Archives of Bückeburg and various independent institutions on the basis of further measurements on papers which had been deacidified in 1995 using the Bückeburg conservation process. The test procedures complied with prevailing standards. Treated and untreated samples, which had been stored under identical conditions, were each examined chemically to determine their pH value and the alkaline reserve as well as mechanically for tensile strength, tensile strength after folding and elongation. The results of the treatment were consistent in every point with our self-imposed goals:

Measurement after 12 years of natural ageing

 

 

1995

2007

 Deviation  

 

untreated

treated

untreated

treated

 

pH value

4.5

10.7

3.8

9.5

150%

Alkaline reserve
(mol/kgt)

/

0.48

/

0.4

 

Alkaline reserve
(% CaCO3)

/

2.41

/

1.95

 

Tensile strength
after folding in N

18

20.5

10.41

15.17

46%

Source: Hubert Höing

 

The natural ageing process of the untreated papers was significantly more advanced than that of the treated papers, as comparison of the pH values shows. In addition, after twelve years the treated paper still had an excellent alkaline reserve. Stability was also re-tested and showed 46 percent higher tensile strength along a well-defined fold in the case of conserved papers in comparison with untreated papers.

The result of testing the longer-term effectiveness of the "Bückeburg process” was thus that the most important goals of conservation treatment are being achieved. The pH value is raised and an alkaline reserve is being established. The values achieved through the treatment persist over a longer period of time. The stability of the paper is significantly increased by the treatment; the increase in stability achieved through the treatment remains after twelve years of natural ageing and is significantly higher than the values for untreated comparable paper.

 

Side effects in the system

Every mass process involves the danger of side effects. Under "side effects” are understood discernable optical-tactile changes whose cause may be deacidification using the Bückeburg process.

Changes in colour
Red and blue tones can become a little lighter as a result of the alkaline medium. Under no circumstances is readability reduced. No ongoing increase in fading during long-term storage has been observed.

Increase in volume
Swelling of the paper and related rippling occurs due to the aqueous deacidification medium. This is reduced by flattening the papers following mechanical conservation, although they may still have minor rippling. The increase in volume is as a rule around 10 percent, but depends very much on the kind of paper.

Halo formation
The majority of inks can be reliably fixed with the added fixative, but in isolated instances stamps and inks can run. However, this never reduces the readability of documents.