Oakum Docka

Flax fibre rope impregnated with pine tar (Stockholm tar)

1kg fills approximately 4–5 linear metres (depending on gap width and depth)

Traditional natural building material

A traditional caulking material used to seal joints and gaps in heritage and conservation work. Common applications include:

• Plugging gaps between timber window frames and surrounding masonry
• Filling joints in timber-framed buildings
• Caulking between deck boards and hull planks in traditional boatbuilding
• Backer material between logs in log structures before lime chinking

Tear off the amount needed and pack firmly into the gap with a caulking iron or similar tool. For external use, cover with burnt sand mastic or linseed oil putty for a weather-tight finish.

Store in a cool, dry place. The pine tar acts as a natural preservative, so the material keeps indefinitely if kept sealed. Wash hands after handling - the tar is sticky but rinses off with soap and warm water.

akum is breathable, which is what makes it suited to traditional and lime-based building. It allows moisture to wick through naturally rather than trapping it, which is essential for the long-term health of historic timber and masonry.