Acetate and PVC laminates and Pressure Sensitive Tape (PST) are frequently encountered on modern/contemporary artworks such as drawings, and on library or archival materials. PST adhesives undergo oxidation and change in consistency and colour (yellowing), become less viscous and penetrate the bulk of the support. Adhesives continue to oxidize, losing adhesive properties in the process, affecting and dissolving certain media such as ballpoint pen inks and felt-tip pens. In daily conservation, a variety of adhesive removal methods are in use, e.g. mechanical, or using solvents (through immersion, poultices), and suction tables, but they all have individual disadvantages and may result in skinning of the medium (mechanical removal), in tidelines (suction table and poultice), or in migration of media that are otherwise stable (immersion). The removal of adhesive residues is equally difficult. To address these challenges, it is important to find a solution that ensures safe and controlled removal with no modification of the artefact and, no residues. Retentive properties of the cleaning tools are important to allow for a gradual cleaning action without tidemarks. Health and safety risks must be avoided and straightforward transfer of the developed technology to end-users is fundamental. It is important to consider that the successful removal of PST has a wide application field even beyond contemporary artefacts. For instance, one of the most important historical objects deteriorating due to PST are the Dead Sea Scrolls, considered to be one of the most important archaeological finds, made up of about 900 documents of major religious and historical significance. PST was used on several fragments, now causing irreversible damage.
Another representative challenge is related to the removal of cellulose acetate, polyvinylchloride (PVC) and other materials used for manuscripts. The issue here is that PVC exudes plasticisers, changing shape and destroying the artefact while acetate deteriorates producing acetic acid, which promotes the deterioration of the very object it is supposed to protect. Besides contemporary works of art, a famous historical case is the Codex Eyckiensis (an illuminated manuscript from the 8th century laminated with PVC), the conservation of which was a major international effort and significantly resource-intensive.
The removal of unwanted contemporary materials from valuable artworks surfaces is also necessary when outdoor murals (Street Art), sculptures, and monuments are vandalized with graffiti. The selective removal of the unwanted re-varnishing is particularly demanding whenever acrylic, vinyl, and alkyd colours were used.
The removal of varnishes and adhesives was addressed by the research activity in WP2.