David Francis is a hands-on mason who has specialised for many years on the memorial side of the stone industry. He was Technical Advisor to the National Association of Memorial Masons, writing manuals and City & Guilds Qualifications. If you have an issue regarding any aspect of memorial masonry, David is happy to help. Send your questions or comments to David at [email protected]
Fixing Memorials with neat cement and the use of Resins.
Much has been said about the use of neat cement for fixing memorials or any masonry units that have a small or thin joint. If the use is appropriate, cement is an effective adhesive. Resins are often thought to be an alternative, but they vary considerably in there composition and applications.
A while ago I was called as an expert witness when a large headstone had been fixed with a sealant designed for use in bathrooms and kitchens.
It was pointed out that the label on the tube stated it was used on aeroplanes. My reply was that it was not used to stick the wings on. On checking how it was used I discovered it water proofed joints inside the fuselage.
Some resins will work, but many do not like being exposed to the elements or UV light.
I have tested resins that are damp tolerant and they work, but are not good enough in the long term because heat and freezing over the years causes the adhesive to fail.
Memorials are expected to remain stable and safe for many years without any maintenance.
Unfortunately, some of the resins used to secure dowels or bolts have caused problems.
A few applications have, after more than 10 years, expanded with enough strength to crack the headstone. Others have shrunk and the headstone has become loose.
At least if shrinkage takes place the memorial remains safe, as long as it was fixed with dowels and holes according to the British Standard.
A problem not always appreciated with granite headstones – or, for that matter, cladding on buildings – is that in direct sunlight the material can more than double the ambient temperature. It can easily become 40ºC or more.
Cement is virtually unaffected by the temperature, but resins often are.
Cement used with granite must be thoroughly mixed into a thick creamy consistency and the joint dampened but not wet. The material being fixed absorbs the cement and the joint is long lasting provided no air bubbles remain in the joint.
Lime mixes are not appropriate for marble or granite, especially for work in cemeteries.
We should all take the cements, limes, resins and other adhesives we use more seriously than we do at present.
We carefully select the stone and the mechanical fixings we use, but how often do we read the manufactures’ instructions on the cement and adhesives we use to insure we apply them correctly so that they will work properly?