What are voorwerkers?
Voorwerkers are the bricks in a wall that are visible. The Dutch term dates from the time when brickworks did not yet distinguish between ordinary bricks and facing bricks. The bricklayer sorted the delivered bricks himself: the finest and best-fired ones became voorwerkers, the rest achterwerkers.
Why sort?
Until around 1900, all bricks came from the same kiln, with large differences in colour, shape and hardness. Bricks that lay close to the fire became harder and darker, bricks further away softer. For the facade, the bricklayer chose the bricks that:
- were straight and well shaped, for neat masonry;
- were well fired and hard, because they are more resistant to frost and rain;
- had an attractive, even colour.
The softer and less attractive bricks, the achterwerkers, went into the core of the wall. External walls at that time were often one and a half or two bricks thick, so there was a lot of core work.
A keursteen was a voorwerker of exceptional quality, used in the eighteenth century for very fine brickwork.
In practice: why it matters in restoration
- When you break out old masonry, you often see that the facing bricks are harder than the bricks behind them. Do not use soft achterwerkers in the facade when repairing: they can be destroyed by frost.
- When filling in a historic facade, look for old bricks or new bricks that match the voorwerkers in size, colour and hardness.
- Choose a pointing mortar that is not harder than the old brick, so that the brick is not damaged.
Repairing a historic facade: checks
- No soft achterwerkers in the facade: They can be destroyed by frost.
- Match the voorwerkers: Use old or new bricks that match in size, colour and hardness.
- Pointing mortar not harder than the old brick: This keeps the brick from being damaged.
Related terms
- Achterwerkers
- Facing brick
- Verblendsteen (veneer brick)
- Brick
- Bond
- Voorschot
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