STONE MONUMENT RESTORATION

Llangefni Town Clock Tower - Llangefni, Isle of Anglesey, North Wales, LL77

Client's Challenge

Isle of Anglesey County Council required a specialist, conservation-led solution to clean and restore a prominent historic stone monument located in the centre of Llangefni.

Over many decades, the monument had been affected by environmental pollution, ingrained grime, weather related staining, biological growth, and graffiti. These issues obscured the original stonework and architectural detail, reducing both the visual impact and the heritage value of the monument.

As a highly visible public landmark within a live town-centre environment, the council required a sensitive restoration approach that would preserve the historic stone fabric while maintaining public safety throughout the works.

Assessment & Planning  

APT ICC met with the client on site to review the areas of concern and assess surface condition, substrate strength, and levels of contamination.

Following this, further discussions were held to agree the most appropriate cleaning and restoration method and the projected results, taking into account the existing condition of the stonework. Where necessary, sample test areas were completed to demonstrate the level of finish that could be achieved and to confirm the agreed approach prior to full works commencing.

This process ensured the selected method was appropriate, effective, and aligned with conservation requirements and client expectations.

    Methodology

    APT ICC delivered the restoration works using a carefully controlled, conservation-led dry soda blasting methodology.

    Dry soda blasting was selected due to its low-abrasion properties, allowing effective removal of pollution, staining, and graffiti while protecting weaker historic stone. The use of a dry process avoided introducing unnecessary moisture into the structure, ensuring the integrity of the stonework was maintained throughout.

    The works were carried out as follows:

    1. Establishment of safe working zones and public protection measures.
    2. Controlled dry soda blasting to remove environmental pollution, ingrained grime, and weathered staining from stone surfaces.
    3. Removal of graffiti from historic masonry using dry soda blasting only, with no chemical graffiti removal methods employed.
    4. Treatment of algae and moss on surrounding stonework and adjacent paved areas to improve safety and appearance.
    5. Ongoing inspection of cleaned areas to ensure conservation standards were maintained throughout.

    This approach successfully revealed the clock tower’s original character and architectural detail while safeguarding the historic fabric.

    Site Access & Logistics

    Equipment
    • Specialist dry soda blasting systems
    • Specialist access equipment (MEWPs)

    Chemicals
    • Wipeout Gel – graffiti removal gel (used only where required on non-blasted areas)
    • Algae Free – algae and biological growth treatment

    All products used were APT in-house formulations, selected for effectiveness
    while remaining suitable for historic and sensitive surfaces.  

    The Results
    • Decades of pollution, grime, and staining successfully removed
    • Graffiti eliminated without damage to stonework
    • Original stone detailing and architectural features revealed
    • Surrounding surfaces cleaned and revitalised 
    • Clock tower restored to a condition befitting its historical importance