Removing the staff bead from an old sash window will reveal a fascinating cross-section of life in the country at the time of repair.
It starts with the timber. There’s usually a clue within the original timber of the sash frame alone to date when it was last overhauled. Georgian and Victorian buildings were typically made from slow-grown softwoods such as Scots pine or imported from other parts of Europe like Baltic redwood, hard dense timber that would last for many years before beginning to decay. Subsequent repairs however are another story. A patch made in the 1940s may well have been made from home-grown softwood, a lighter coloured timber than the original with much wider, open, straighter growth rings, which would have been the only timber available at the time due to wartime restrictions having been imposed on imports.
Next the adhesive. As mentioned, joinery adhesives were, until the mid C20, made from animal hide, usually mixed with water and then boiled for extended periods to dissolve the bones and hides. These adhesives, known as hide glues, dry to a hard, yet brittle film which will, with the passing of time, crack and fail in a very specific manner. If the joint is held together with a flexible film that peels away as opposed to crumbling, then it is likely to have been held together with a synthetic resin adhesive, most commonly used from the late 1940s onwards.
Fasteners are also readable. Hand cut nails have tapered shanks and were cut by hand. Wire nails are round in cross section and were machine made. In Britain wire nails became common in the 1890s. A screw with a single slot and tapered tip is pre 1930s whilst a cross head screw is younger still. Historic England’s guide to historic timber repairs looks at the various materials used in joinery and their dates and how to recognise them when assessing historic joinery. The joiner’s marks left by earlier joiners are also important to recognise and Historic England also give advice on this in their guide to historic timber repairs. There is a useful background explanation of Historic England’s guidance on historic timber repairs.
The painted-over shim is perhaps the most telling thing of all. A thin piece of wood had been inserted between the frame and the sash box, to straighten a frame that had begun to rack. And once straight, it had been painted three times, and then left.
Good sash window repair today leaves its own layer in this record – the epoxy consolidants, the stainless fixings, the particular filler profiles that will puzzle someone in 2125. For Sash Window Repair contact www.sashwindowpreservation.co.uk/services/sash-window-repair/.
Each generation of joiners has left their mark on a building whether they meant to or not.