Full stone preparation
When beginning the conservation or restoration of a stone structure, building or memorial, an important first step is determining the extent of work required for the project. To assist with this process, the Classical Stone team will be happy to consult with you or your architect on-site.
We will carry out a site survey and condition reporting, and determine the methods to achieve the best outcomes for your stonemasonry project, working within current historical practices and principles. For most projects, our team will consider the need for templating, stone selection, banker work and fixing.
Classical Stone’s in-house drawing office is equipped with a full size cutting table, allowing us to produce the largest of stone building templates. Template and pattern making is a specialist trade itself, requiring an understanding of the stone, its characteristics, and the finish being sought. Often, many stone building templates can be required in order to produce just one stone.
In addition to templates, we also produce our own plaster and clay models as required when undertaking stone carving or sculpture. This can assist with adorned building work such as decorated corbels or bosses, acanthus leaves, or finely detailed sculpture.
We take great care when selecting new stone for conservation or restoration work, to ensure the ‘fabric’ of the building remains consistent. At Classical Stone we carefully consider all aspects of the original stone; not only the stone colour and markings, but also the stone density, porosity, and weathering characteristics.
Our first preference is for replacement stone to be sourced from the same quarry as was used for the original construction. But of course, this may not always be possible if the original quarry is no longer operating. In other cases, even though the quarry is still in business, the geological characteristics of the stone may have changed over time so that it no longer matches the original material.
We believe this meticulous approach is critical, especially when stone indent repair is called for. The new stone indent must work in harmony with the original stone, allowing equivalent moisture egress and aging similarities.
Banker masonry work
Classical Stone’s banker masons work meticulously to reproduce the shape and form of the decayed or failed building stone being replaced.
We know and understand stone. Our craftsmen ‘feel’ stone through their chisels, ‘recognise’ stone through their deft touch, and ‘see’ the story of stone with a trained eye.
Our banker masons work to avoid the unsightly appearance of circular scars left by large profiling saws, or lines tracked across the face of replacement stone from wire saws. We believe this is no way to attend to stone restoration projects, and indicates poorly skilled workmanship and a lack of understanding of the conservation and restoration ethic.
Instead, our team take enormous pride in using the skills, methods, and tools that traditional stonemasons and craftsmen have used for centuries. We believe that only with these ancient masonry skills and work methods can true stone conservation be achieved.
The capable handling and bedding of building stone is a skillset gained only through years of experience. Classical Stone’s fixer masons understand both the dense weight and fragile nature of stone.
Our attention to detail when working with site set out, lifting and replacement of new stone components or forms, ensures our finished work is both true to the building’s integrity and pleasing to the eye.
Fine stone carving & lettering
All our stone letter cutting and carving is carried out with traditional hand work, instead of the CNC or laser stone cutting methods now common in most stone masonry companies. This hand cut, hand finish gives the Classical Stone team maximum flexibility when matching existing work, adding inscriptions or indented elements on carved or sculptured stone pieces.
Our very talented stone cutters and carvers will talk to you about the fine detail you need for your stone project. When working on special pieces, our stone masons model in clay or plaster prior to working the stone, to ensure outstanding results.
Cleaning of aged stone
At Classical Stone we work with architects and you as our client, to produce a sample benchmark of the expected standard of clean for particular stone. In this way, we ensure your expectations for cleaning of historic masonry or sculpture are met. We offer the traditional low pressure jet method, as well as our preferred method of superheated water cleaning of stone.
Superheated steam water systems (such as our US-made Sioux machine and UK-built Thermatech) clean stone by removing build-up, including paints and atmospheric pollutants. Superheated steam cleaners have the added benefit of killing microbial spores on stone, thus preventing the quick regrowth of damaging lichens and moulds. We also offer stone poultice cleaning for removing embedded stains, such as copper or iron, from stone.
When should aged stone be cleaned?
The decision on whether to clean a stone structure, building or monument shouldn’t necessarily be made solely for aesthetic reasons. Rather, an expert stone cleaning program should have real benefits for the stone structure, through reducing the rate of decay or deterioration.
Built-up dirt or pollutants can accelerate the growth of biological matter, which in turn hastens the erosion and decay of stone surfaces and mortars. With careful, considered attention to cleaning, Classical Stone can safely remove this built-up matter from stone, both to prolong the life of the stone and enhance its appearance.
What is the best way to clean aged stone?
After the decision to clean historic stone or masonry has been made, Classical Stone will consult with heritage architects to confirm the method and extent of the stone cleaning. At this stage we will usually perform a ‘conservation clean’, to remove unwanted material from stone and leave the natural patina on the surface.
Stone mortar repair
Sympathetic, high quality stone mortar repair calls for both a detailed understanding of the process, together with the competency to perform that process. The Classical Stone team possesses both these critical assets.
We begin the stone mortar repair process by providing a sample of the repair mortar for colour approval, by you or your architect. This attention to detail is the first step to a successful stone mortar repair project.
At Classical Stone we only use natural lime mortars for stone elements in need of mortar repair. By doing this, we ensure the repaired stone is able to breathe, a critical factor in the long-term integrity of the piece.
As time passes, weathering and decay commonly cause gaps to appear in stone masonry mortar, causing problems as water enters the stone structure. To prevent this issue, the Classical Stone team are highly experienced in all forms of stone structure repointing, as well as the various finishes and repointing techniques traditionally used.
The strength of the mortar and pointing material can affect the integrity of the entire stone piece and its surface. This critical nature makes stone repointing an often misunderstood component of stone conservation.
By choosing the right flexibility and porosity of stone mortar, we ensure the masonry is able to swell and expel moisture through the joints, rather than forcing it through the face of the stone and causing delaminating or fretting.
Mortar analysis provides a good foundation for stone repointing
Classical Stone can provide mortar analysis on the existing bedding and mortars to ensure the best possible match in terms of strength and colour. We can also provide you with samples of sands for approval of grade and colour before we begin.
Mortar analysis can also reveal when a previous repointing project has used material which is incompatible with the type of stone in the structure. In this case, Classical Stone can recommend an alternative repointing material which is a better fit for your particular stone.
Classical Stone can also provide affiliated masonry services such as:
- Site overlay
- 3D modelling
- Hand forged iron work
- Traditional plumbing – lead, copper, and slate