130 THE BUILDING CONSERVATION DIRECTORY 2025 CATHEDRAL COMMUNICATIONS For managed sites and buildings the risk of graffiti should be anticipated and a coping strategy built into the maintenance plan. Negotiating with the conservation officer a pre-approved methodology and contractor will avoid delay. A ‘log’ of graffiti incidents and removal should be maintained to inform future treatment. At the first opportunity and before any treatment, the graffiti is inspected and assessed by a nominated conservation professional. The ambition is always to return the substrate to its pre-graffiti condition but the substrate, patina and organic growth can be harmed by both the graffiti and its removal. The assessment needs to include: General location; is it close to a water course or within a scheduled monument? Is vehicle access difficult? The substrate; identify its type and condition, and its likely resilience under treatment; The coating; establish what it is, its thickness and its likely acquiescence to treatment. Make a shortlist of the techniques deemed efficacious and discriminating. Carry out small scale and discreet trials if permitted or required for LBC. A reasonable aim is that text or symbols should no longer be legible to a new observer. There will be no visible loss of sound substrate: the degree of removal should be compromised, rather than wringing-out the last remnants of pigment. Remaining translucent pigment will normally fade naturally in sunlight. REMOVAL TECHNIQUES The examination and consent process (for LBC in particular) should identify the constraints which the appointed contractor or conservator will need to heed. Thereafter it is normally the operative who decides which techniques to adopt but the sequence should be stepped, starting with the least hazardous method or reagent as guided by the product data sheets, and begin in a discreet location. Dry brushing for example is a prudent first step to remove paint from a dusty or A graffiti panel midway through its removal from the lime plastered brickwork of a Grade 1 listed ruin: the right hand half has been removed using alcohol-based graffiti gel followed by two secondary treatments to remove ghosting; hypochlorite based ghost gel and then acetic acid (white vinegar). Both secondary treatments were applied to a wet surface to limit the penetration depth, each kept to 2–3 minutes dwell time before removal with superheated water. Vacuum recovery was necessary due to the close proximity of a river. Graffiti removal from a scheduled monument that is also an SSSI. Superheated-water is sprayed within a vacuum enclosure head, melting and rinsing the acrylic paint which is drawn away to a vacuum below. organic substrate; next, supplement this with water, then hot water and so forth, before adopting chemical agents. If the target area is small, it may be possible to apply and remove reagents by hand (brush and cloth) but active ingredients must not be left in the substrate once dry. For this reason, larger scale work will normally require pressurised water rinsing. In order to release the pigment, we must first destroy or displace the binder, using either hot water or solvents, or both. Removing residual pigment ‘ghosting’ after this will normally require either a bleach, a weak acid or a strong alkali. All three can generate salts, introducing the risk of salt crystallisation within a mineral substrate and consequently disaggregation and spalling. Using reagents in poultice form followed by removal and thorough rinsing helps ensure the drawing away of harmful residues. Organic solvents such as xylene and dichloromethane will readily dissolve organic binders and will work down to lower temperatures (0°C) than alcohols Left: Tagging removal from a modern limestone wall, part of a grade 1 listed ruin, following a typical two- to three-part process. Middle: Ghosting remains after an initial wash with superheated water followed by alcohol graffiti gel application at 30-minute dwell: repeat treatment was required due to the overlapping layers. Right: The last step was repeated applications of hypochlorite ‘ghost’ remover gel to the wet surface, each with 5-minutes dwell, then wiped with a sponge and rinsed with superheated water. Ghosting treatment repeated.
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