Fuel Use
At the start of Day One, the firing chamber was at 22°C, and it took about 50kg of Opepe and about two hours 20 minutes to reach 1000°C, at an average rate of about 21 kilos per hour.

On the second, third, fourth and fifth morning, by the time the furnace was ready to light, the temperature in the firing chamber was around 215°C, and the furnace took about two hours to reach 1000°C, using only about 40kg of Opepe, at an average rate of about 20 kilos per hour.

To fire the furnace to an average working temperature of 1053°C, we used 880.25 kilos (0.88025 tonnes) of wood over five days, at an average rate of 14.45 kilos per hour, or 176.05 kilos for each average 12.20 hour firing day.

About one to one and a half small shovelfuls of ash were emptied from the firing chamber each morning.

Shelf Collapse
On the last morning of the firing, the shelf nearer to the stoke hole had tilted and partially collapsed, resulting in some spillage of cobalt blue glass. The cause was that one of the small shelf supports had broken away, allowing one end of the support bar to dip sharply down into the firing chamber. Luckily, we noticed this very soon after it had happened, and were able to re-site the support bar whilst the furnace was still being fired.

Over the five days, the lehr consumed an average of 3.35kg/hr of Oak and Opepe at an average temperature of 480°C, rising to 500°C for about 30 minutes at the end of each day before shutting it down.

As before, we kept the stoke hole closed down (damped down) to save fuel.

Each morning, we removed less than a shovelful of ash and charcoal from the lehr firing chamber before re-lighting.