The Chemistry of Cleaning

The Chemistry of Cleaning

When Mark Rothko’s work of art “Black on Maroon” was defaced by graffiti, chemists at Dow teamed with art restoration and conservation experts at the Tate Modern to get the restoration right.

This remarkable example illustrates the principle of solvent selection when faced with a particularly difficult cleaning problem. In this case chemists had to find a solvent (actually two were used) that readily dissolved the ink, yet preserving the base ink used in the artwork. It sounds simple enough, but finding a solvent which is selective to the different inks takes lots patience and knowledge of the chemistry of the inks (and surface materials).

Solvents work on the principle of ‘like dissolves like’ – substances dissolve into their compatible solvents and in varying degrees in part-compatible solvents. A very simple example: sugar and salt are both water soluble and so will completely dissolve in water (the solvent), yet only sparingly soluble in alcohol (another solvent). So, if you know the chemistry of the material you are trying remove (ink) and the chemistry of the material you are trying to preserve (the inks in the artwork), you can find a solvent that dissolves the ink completely and yet sparlingly (or preferably not at all) dissolves the artwork inks.

 

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Rafael Cobos
rafcobos@futurecleansystems.com