At Stourbridge, we noticed that raising the logs to introduce air under them produced a better burn.

Before re re-erecting the furnace we built a firepit so that we could introduce more air into the furnace and set the fire on a grate, with the object of producing a more efficient burn. This is, of course, exactly how wood-fired pottery kilns are fired, so should work with a wood-fired glassworking furnace.

We designed a keyhole-shaped firepit, with a slope upwards from the centre of the base (which is about 4" below ground level) towards the stoking end, and upwards towards the ash-emptying hole at the back of the furnace. The grate, when it was eventually added, echoed this upward slope.

The reason for making sloping instead of horizontal floors was to allow for the easy emptying of ash by scraping it up each slope and straight out of the furnace. Also, having a hole at the back of the furnace enabled us to keep the fire going instead of having to pull the fire back for ash-emptying as we had to do in our 2005 and 2006 furnaces.

Adding the sloping firepit also meant that we did not have to raise the stokehole and its tunnel to insert the fire bars and to empty ash at ground-level.

We used thick Roman tile fragments, cemented into place with daub which was laid over a layer of sieved soil and small stones. This layer allowed us to smooth out the initial hole for the firepit and to get the slopes correct. The side walls, built on top of the floor, provided the support for the furnace and stoke hole tunnel.

After the first two firings we added the grate, made from the stainless steel bars which we had used to support the pots in the furnace at Stourbridge. These were held in place by a one inch-thick wall of daub set against the side walls of the stoke hole. This page details the building of the grate.

The result of adding the firepit and fire bars was to achieve higher temperatures and to allow all of the charcoal to burn to ash.