Vogelensangh bakes bricks in the only coal-fired ring kiln in the Netherlands. The pallet of bricks is transported inside through one of the 20 portals. Then the fire in the ring kiln makes a complete revolution in 10 days, firing the bricks at a temperature of around 1,060 degrees Celsius. That temperature is reached because stokers throw coals through the stoke holes into the kiln day and night.