conservation

research & diagnosis

forms

Ion Chromatography (IC) form for glass

Ion chromatography makes it possible to measure the concentration of salts deposited on a glass surface as a result of atmospheric degradation. See IC analysis.
To view completed forms, see objects.

Explanation

1. The form contains a section that briefly repeats data from The Museum System (TMS), with a small photo for identification.

2. The General Condition field briefly summarises information from the object’s history. The general condition listed in the right-hand field is based on findings made during sampling. The categorisation was carried out by Guus Verhaar and does not correspond to the General Condition field in TMS–Conservation Studio.
Red = very poor, orange = poor, green = good, and grey = unknown.

3. The Examination and analysis field briefly summarises the IC analysis results along with the category to which the object belongs: likely unstable, potentially unstable, or likely stable. This categorisation is based on the results shown in the lower table to the left of the bottom graph (based on sodium AND potassium concentrations).
a. Anything below the orange line (LOQ*) is likely stable
b. Anything between the orange line (LOQ) and the red line is potentially unstable
c. Anything above the red line is likely unstable.
The LOQ (limit of quantification) is a parameter of an analytical measurement method. Below this threshold, the method cannot reliably determine the concentration; above it, it can.

4. The standard deviation is not included in the top two graphs, but it is included in the bottom graph (see the raw data table on the left). These error bars represent the standard deviation (SD) of the measurement results. The SD is therefore an indication of the measurement error. As a result, significant variation in the results for each object may occur.

5. The upper two graphs or figures are different on every card! This is because the axis scale varies depending on the object (the data from the table determine the axis scale of the bar graph on the right!).

6. High ion concentrations ultimately correspond to poor condition. However, low concentrations do not always correspond to good visual condition. In some cases, objects with low ion concentrations have also been classified, according to the Guus Verhaar method, as ‘very poor’.

7. The ‘Interpretations, questions and comments on results’ field contains all findings in written form, along with references to the object and the 2023 visual results.

8. The most important findings are based on a number of objects that were analysed by IC twice, in 2017 and 2020.
– Comparing these results makes it possible to track the ‘progression’ of glass disease.
– Only object 911 (KN&V) showed clear evidence of degradation products forming on the surface (a moist layer). No notable difference was visible to the naked eye in the other objects.

9. Not detected: F-, NO2-, Br-, NO3-, PO43-, Li+, NH4+, Mg2+

10. Sodium and potassium are almost never dominant at the same time. When a high concentration of potassium is observed, little to no sodium is detected, and vice versa.

11. Acetate and formate are the two anions most frequently detected on unstable glass, and this is also the case in this dataset.

12. Carbonate is associated with the degradation of historical glass, but the IC measurement method used is not particularly sensitive to carbonate, hence the large margins of error.

13. Sulphate was detected on two objects, but its origin remains unclear at present. It could be related to a former archaeological context or a past cleaning treatment. Further research is needed to determine this.

14. Suggestions for further research are listed in the bottom field.