A roll moulding is a simple round enrichment — a half-round or three-quarter-round bar — running around an opening or along an arris. It appears around portals, windows and niches, on wall corners and as the profile of a pilaster. In Dutch it is called a kraalprofiel, in English also a bowtell or bowtell moulding.
Where it comes from
The roll moulding is characteristic of Romanesque-Gothic work, and in the Netherlands it is best known from the brick churches of the north (Groningen, Friesland, Drenthe). There the profile was built up from specially made moulded bricks: the roll runs around the reveals of a pointed-arch window or a portal and gives the opening depth.
What it does
- Creates depth. An opening in solid masonry is a flat hole. A roll in the reveal lets light and shadow travel around the opening, so the wall reads as thicker and the window as richer.
- Protects the arris. A rounded corner chips far less readily than a sharp one — at a doorway people walk past daily, that matters.
- Sheds water. On an external profile, rainwater runs off the curve instead of standing in a sharp quirk.
Making and repairing it
- Masonry — with moulded (purpose-made) bricks. In restoration, missing units are made to match or cut from a solid brick; the profile has to run through exactly, or the break shows immediately.
- Stone — cut from the block, using a template so the profile stays constant over its full length.
- Plaster and timber — run with a running mould or cut with a router, forming the profile on the arris of a pilaster or reveal.
The usual conservation rule applies to repairs: first establish why the moulding has decayed — normally penetrating damp or frost — and remove that cause. Otherwise the new work is back where it started after a couple of winters.
Related terms
- Bead
- Moulded brick
- Reveal
- Pilaster
- Pointed arch
- Brick Gothic
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