Dealing with Graffiti at Historic Places

Historic places are unfortunately fair game for graffiti attacks – sometimes especially so when these places are visible and widely recognized landmarks. Defined as writing or drawings scribbled, scratched, or painted illicitly onto walls and other surfaces, graffiti from a heritage conservation perspective is an intervention to be removed or reversed. It clearly differs from old markings that are an acknowledged and legitimate part, or “character-defining element”, of a historic place. Examples of the latter are prisoners’ inscriptions etched into the basement cell walls of the Cardston Courthouse or, on the opposite side of the law, North West Mounted Police members’ initials carved into the sandstone outcrops overlooking Police Coulee at Writing-On-Stone Provincial Park. These special cases contribute to heritage value rather than obscure or detract from it.

However one sees graffiti, its removal diverts resources that could otherwise preserve and maintain historic places. Lasting damage takes a toll on these places’ integrity and takes away, even if only incrementally, from the legacy they embody for present and future generations.

The understandable impulse to expunge unsightly graffiti as soon as possible, the possibility of follow-up or copycat attacks and, in some cases, local bylaw requirements all urge timely actions to remove graffiti. As with any conservation effort, problems can arise when the consequences for historic fabric aren’t fully considered. Inappropriate removal methods can leave more permanent scars – a case of the cure being worse than the disease – and repeated attacks and interventions amplify these impacts. This brief post looks at minimizing impacts through good planning.

A qualified contractor and Historic Resources Management Branch staff remove graffiti from the “Big Rock” erratic west of Okotoks, a Provincial Historic Resource. Below, graffiti removal from a 1912 building leaves eroded mortar joints and permanently pitted historic brick.
A qualified contractor and Historic Resources Management Branch staff remove graffiti from the “Big Rock” erratic west of Okotoks, a Provincial Historic Resource. Below, graffiti removal from a 1912 building leaves eroded mortar joints and permanently pitted historic brick.

The potentially damaging effects of abrasive cleaning methods on historic buildings are well known but sandblasting, soda and other grit blasting methods are go-to methods for quick graffiti removal even today. While abrasive cleaning methods can have their place, the irreversible impacts of sandblasting historic brick, for example, include pitted, porous surfaces that are susceptible to soiling and actually more difficult to clean in future graffiti attacks. Pitted, sandblasted brick more readily absorbs moisture and is especially vulnerable to freeze-thaw damage, with dire implications for the material’s long term survival. Specialized and even exotic treatments involving dry ice, walnut shells, glass beads and even sponge exist and can be safe and effective, but graffiti removal in a conservation framework begins with a minimal intervention approach guided by thorough understanding of the cleaning methods and the properties of the materials involved.

Specially formulated chemical paint strippers have a long track record of successful spray paint removal from historic sites. Selection of the appropriate product will depend in part on the nature of the material. Acidic cleaners, for example, may etch polished granite or glass and attack the lime mortars in historic masonry and the calcite binder in Alberta sandstones. The many variables in cleaning procedures include the methods of stripper application to affected surfaces; surface “dwell times”; protection against premature drying of the stripper from sun and wind; environmental considerations; and careful but thorough washing to remove paint and chemical residue. High-pressure powerwashing can leave pitting similar to sandblasting (see photograph above), while saturating walls can damage interior finishes and put masonry at risk of frost damage in shoulder seasons. Alberta’s traditionally long winters add to our graffiti removal challenges.

Since requirements vary from case to case, a plan of graffiti counterattack can start with knowing local regulations, finding local graffiti removal contractors, and understanding the requirements of the historic place and its materials by consulting with the Heritage Conservation Adviser for your area, and referring to online resources like those listed below at the end of this post. Owners of designated historic resources also need approval for graffiti removal from the Province or municipality (or both), as they would for other interventions. Graffiti preparedness could include pre-approval for removal methods that have been tested as suitable for a particular resource or material.

Graffiti prevention plays an important role and can include physical barriers to rooftops or other vulnerable areas and, possibly, “shelter coats” and so-called graffiti repellent coatings – all of which need to be investigated and evaluated for their effectiveness and possible impacts on historic fabric. Other measures include better monitoring of vulnerable areas, having “eyes on the street” in urban areas, community planning, and promoting awareness on the impacts of graffiti on public spaces and historic places. One such program for the “Big Rock” erratic, a Provincial Historic Resource near Okotoks (photograph above), emphasizes how spray paint on seemingly bare rock in fact obliterates a welter of ochre smudges and pictographs placed there centuries ago by First Nations.

Planning is one of the underlying principles of the Standards and Guidelines for the Conservation of Historic Places in Canada. Graffiti will hopefully never be an issue at your historic places, but it helps to have resources to deal with it if it does.

Written By: Fraser Shaw, Heritage Conservation Adviser

Please see also:

Graffiti on Historic Surfaces, by Stephen Gordon

New York Landmarks Conservancy: Graffiti Removal Technical Tips

English Heritage: Graffiti on Historic Buildings and Monuments – Methods of Removal and Prevention

U.S. National Parks Service Preservation Brief No. 38: Removing Graffiti from Historic Masonry, by Martin Weaver

Historic Scotland Technical Advice Note 18: The Treatment of Graffiti on Historic Surfaces

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