Application note 202002: analysis of varnish

If you want to repair or retouch fine art, it is essential to use treatment that coincide with the existing materials of the painting. It is also useful if the analyses of those materials is as minimally invasive as possible.

JBL Science have a range of tools at our disposal to get as much information as possible from minuscule amounts of sample. We can analyse pigments present in paint using raman microscopy to define palette, using an external probe that is completely non-invasive. This process can also help to define provenance of art pieces.

Just as important as the paint is to determine the identity of any varnish coat, so that it can be removed or replaced as effectively as possible and the Application Note below shows how we can apply gas chromatography-mass spectrometry (GC-MS) to investigate molecules present in the varnish.

Using only milligram quantities of varnish, scraped carefully from the surface of the painting, we take an approach involving hydrolysis of the varnish, chemical labelling and analysis of the derivatised fatty acids. By quantifying the levels of the various fatty acids we can tell the origin of the varnish and also whether or not it has been pre-treated. The fatty acids that we would typically detect and quantify include palmitate, stearate, azelate, suberate and sebacate, but our MS analysts have many years of experience in detection and identification of unknown compounds.

JBL Science can provide a comprehensive analytical workflow for all your fine art needs and we also work closely with our fantastic colleagues at Lincoln Conservation who provide significant expertise in restoration processes. Please contact either partner to discuss other research needs.

To read the full application note, download the PDF file by clicking here.

For further information, please get in touch through the contact form or contact the lead scientist Dr. Andy Gill.

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