Tuesday, 16 September 2008
Monday, 15 September 2008
It tasted good, once I cut the top off... I need to retard the bread in the fridge until the oven's cooled down enough - it's so well insulated now that it only cools about 9C an hour when it's about 250-300C!
Friday, 27 June 2008
And this was the result - the first pizza! Actually, this was the second pizza, as the first was sadly offered to the fire gods due to circumstances beyond my control (gravity and clumsiness with a pizza peel). It tasted at least as good as it looked - mozzarella, basil & tomato.
The recipe came from the Forno Bravo pizza cookery book - the best one I've seen on wood fired pizza, and better still, it's free. You can download a copy here:
This was a great moment - finally something to eat from my hours of hard work.
Next - bread!
Here's the inside, with some of my firewood stacked up (thanks to my friend the tree surgeon for that - only 2 tons left to split now, and then I can have my front lawn back). The pine table and chairs were second hand from ebay - £25 the lot. I bought the peels, while the rest of the tools were made from scrap landrover aluminium and broom handles. Here's those fancy LED switches that I built into the flint block walls - the red one works the thermometer, while the blue one... ... works a 12V halogen light fitted in the rafters, shown below. It's just the right angle to shine into the oven, so I can see what I'm cooking. The power for these comes courtesy of an old car battery, charged by a 5W solar panel fitted to the roof. The bracket for the 12V light is more scrap aluminium (see - I told you all that junk would be useful one day).
And finally, below, is the instruction manual. Much prettier than my original notes on which thermocouple was placed where. The drawing was burnt into the wood (a salavaged scrap oak floorboard offcut) using a soldering iron, then treated with linseed oil afterwards. The numbers 1-6 remind me where my thermocouples are placed - so I can select the right one using the rotary switch on the front of the oven.
Next - start cooking!
Monday, 23 June 2008
Thursday, 29 May 2008
I was pleased with this, and moved on to insulating the back of the door. I spent a long time moulding a nice plug for the door entry out of my insulating mix (vermiculite, fireclay, cement and sodium silicate), attaching it to the back of the oak with metal ties. The insulating mix dried, cracked a bit, dried some more, then fell apart when I lifted the door up.
Lesson 1: my insulating mix is good for filling cracks, and coating chimney insides. It's not good for making doors.
Door number 2 was made by using the wooden front from door number 1, then carving two thermalite blocks to act as a plug for the oven. They were fixed to the oak door using screws - the carving was very easy thanks to the softness of the blocks. This looked promising.
Pleased with this, I had a nice big fire and stuck the door in place after the coals had cooled off for 10 minutes. By watching the temperature (graphs in C and F here, C top, F below)...
... I could see that this door worked well. Notice that this graph's over 28h, and the dome surface now takes 6 hours to cool from 300C to 200C - twice as long as it did without the door. I thought I'd cracked it, but unfortunately:
- the sodium silicate round the edges of the door had erupted into a white fuzzy mass in the heat, and looked horrible
- the wood around the door had charred badly, causing the aluminium frame to come loose, and in one place, fall off
- the wood on the back of the door had warped with the heat and cracked, causing the thermalite block to move and crack as the wood bent. You can see one of the big cracks in the block below. The bit at the bottom is a loose chunk that fell off when I lifted the door.
The second large fire was earlier in the day, so easier to measure for longer without staying up half the night. The dome surface (red line) got up to 600C, while the hearth brick only got up to 400C. The vermiculite was still steaming on this burn - it's absorbed lots of water from the mortar. You can see how the temperatures rapidly drop after the fire is finished (about 4h on this graph below), then soon even out to a more steady decline. At present, the oven dome surface takes about 4 hours to drop from 300C to 200C. Most of this heat will go out of the open oven front - there's no door on this yet.
Here's the same graph with a Farenheit scale for those who prefer it in old money...
You can see how all the heat is locked up deep in the clay dome - the 2" deep probe is always the hottest, and gives up its heat to the dome surface and outer surface. The temperature below the thermalite blocks never goes above 45C. I need a door!