Why Is That Wall Covered in Raised Patterns? Plaster Pushed About While Wet
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External plaster worked into raised or incised decoration covers the fronts of timber-framed houses across parts of eastern England. The technique is simple and the window for doing it is short.
What the technique is
Timber-framed buildings were frequently rendered externally to protect the frame and the infill panels from weather, using a lime plaster applied in coats. While the final coat is still soft it can be worked, and that is the whole technique. Patterns are pressed in with a shaped comb or a carved wooden block, incised with a point, or built up in relief by adding further material and modelling it by hand. The work must be finished before the lime sets, which gives a few hours at most, so the design is planned and the craftsman works fast across a whole panel.
The kinds of pattern
Designs fall into recognisable categories of increasing ambition:
- •Combed patterns of fans, chevrons and scallops, made with a notched tool
- •Repeating stamped motifs from a carved block
- •Incised lines outlining panels and framing openings
- •Raised strapwork, foliage, flowers and vines modelled by hand
- •Figures, animals, coats of arms and dates
- •Whole scenes, on the most elaborate surviving fronts
Why lime rather than cement
The material matters enormously and using the wrong one destroys the building it is meant to protect. Lime plaster is soft, permeable and slightly flexible, so it allows moisture in the timber and the infill to escape outward and it accommodates the seasonal movement of a timber frame without cracking. Cement render is hard, impermeable and rigid, so it traps moisture behind it against the timber, which rots, and it cracks as the frame moves, admitting water that then cannot get out. A great many historic buildings were rendered in cement during the twentieth century and are now being stripped back at considerable cost.
How it is repaired
Conserving decorated plasterwork requires decisions that are genuinely difficult, and the approaches differ. Cleaning removes generations of limewash that have softened the detail, which is standard and reveals what is underneath, sometimes including earlier schemes. Losses can be left as losses, which is honest and can look neglected, or filled in matching lime mortar left slightly below the original surface so the repair is legible at close range, which is the usual conservation compromise. Recreating missing ornament to match surviving work is done where enough evidence exists. Recarving a whole panel from a photograph is restoration rather than conservation and is contested.
Where it survives
The concentration is striking and follows building materials rather than any cultural boundary. East Anglia, and Suffolk and Essex in particular, hold the great majority of surviving work, because the region had abundant timber framing, no good building stone, and a prosperous cloth trade that supplied both the money and the desire to display it. The elaborate examples date largely from the seventeenth century. Comparable traditions exist elsewhere in Europe, notably in Germany and Austria. The craft nearly died and has been revived through conservation work and through a small number of practitioners, and new decorative work is now occasionally commissioned.
The takeaway
Working the final coat of external lime plaster while it is still soft, by combing, stamping, incising or modelling by hand, gives a few hours to complete a panel. Lime is used because it lets moisture escape and moves with a timber frame, where cement traps water against the timber and cracks. Suffolk and Essex hold most surviving work, funded by the cloth trade.