It's been almost a year and a half since Craig Miller towed the Gypsy Woodfired Bakery Experience, our 'mobile bakery', to Tipperary Farm, and I fired up Luna for her first serious bake. Since then, I have baked something like 15,000 loaves of bread in Luna the woodfired oven, and spent well over 600 hours in the Gypsy bakery, making sourdough bread and teaching people how to make sourdough bread.
In that time, I've continued to learn on the job, and Craig and I have continued to tweak this 'relocatable bakery'. I hesitate to call it a 'mobile bakery', as was the design brief. It's not really mobile. Once again, weight has been the enemy, despite all the best laid plans.
The Plan, and how it's changed - for now
Originally, the idea was to get the whole bakery built on the trailer, and for it to weigh less than three tonnes. We did our 'back of the paper bag' weight calculations (as Craig and I are prone to do) many times, and arrived at an estimate of 2.8 tonnes. Even when we were being generous with our 'guesstimates', we could only get to 3.2 tonnes all up.
I suppose a bit of context is important here. Craig's folks live on a farm at a place called Wallarobba, near Dungog in NSW. This is where we did most of the building of both Luna and the Gypsy trailer. On the farm, we have a big shed, a tractor, some welding gear, and a workshop. Most importantly, there is space to build big stuff. We don't have computer assisted thingamybobs, or scales, or even a cement floor.
When we decide to free up some time to build things, Craig and I just have a few phone conferences beforehand, decide on a plan of work, pick up or assemble the necessary hardware and materials, meet at the farm and get to work. Our projects usually happen over two or three sessions, sometimes months apart. At the farm, we are about 50 kilometres from the nearest hardware store, and about 120 klms from the nearest steel fabrication shop. If we haven't got what we need when we get there, we just have to improvise.
During this particular build, I would say that things went reasonably closely to plan - but there were still quite a few changes made each time we returned to continue the job some weeks or months later. For one thing, the trailer chassis had to be rebuilt, as we could see it wasn't up to the task. We didn't actually put the trailer over the weighbridge at that time - we just beefed it up and carried on.
Come rego time a year later, it was necessary to weigh our almost finished creation. Thinking there might have been a bit of a weight issue, I removed all the bricks from Luna's belly. I proceeded to the weighbridge and held my breath. 3.6 tonnes. Oh dear. That was without the bricks, without dough, water or firewood. And without a coolroom motor, which is yet to be installed.
Prior to this, we had just rebuilt the trailer to handle 3 tonnes. With everything on board, it would now weigh over 4. That's a tonne more than planned, and a tonne more than the rebuilt suspension system was designed handle.
My daughter was unimpressed. 'How could you make such a huge error of calculation?', she asked. I agree that it is a lot heavier than anticipated. But it just isn't possible to weigh every piece of wood, every bit of metal, every sheet of stainless steel, every extra brick added to tune the oven once it was installed and operating. Particularly when things change over the course of the build. Every little thing added over the past twelve months has indeed contributed to our trailer becoming not 'mobile' but 'relocatable'.
Now it lives and works at the bottom of our garden, rather than onsite at whatever market or event is on each week.
Meanwhile, back at the relocatable bakery
Despite this amendment to the design and usage brief, the actual bakery kitchen is very functional. Every Friday night, I can be found set up at the front of our property, with the oven fully fired, baking a few hundred loaves of sensational sourdough bread.
The small workspace is well organised and efficient, with nothing unnecessary on board. I have created an ergonomic working area, with a few things still to do to make the space easier to live with - but in the main, I have to say it is one of the best baking areas I have ever had. I have hot and cold water, the hot coming from the oven, so needing no power to achieve. I have plenty of light, and room enough to move a large baker's peel. I have a workbench, shelves for wooden proofing boards, and an adequate dumpout for cooked bread. The proofer, powered by a slow cooker at present, works perfectly, and the coolroom, while not yet finished, does the job well enough, using ice and some fan blowers. It will be substantially better when I can afford to put in a proper coolroom motor though.
At this point, the whole thing would be within spitting distance of being finished - though I'm sure we will always be fiddling around with it in the name of both improvement and science.
Driving Luna, the woodfired oven
I now understand how to drive the oven on the trailer with a degree of precision. There are a few tricks to getting the oven just right - to do with how you run the fire, and what you use to make the fire. I've tried quite a few different techniques and timbers so far. In terms of fuel, I've settled on scrap timber from the local sawmill, as it is both a cheap waste resource and perfectly suited to the type of fire Luna prefers. Scrap timber is very small in diameter, which means that it delivers lots of flame and not too much hot coal. Flame is essential to rapidly transport hot flue gases around the top decks of the oven. The timber scraps are hardwood from garden stakes and floorboards, cut in reasonably short lengths. While it could be better seasoned, even when it's green it burns well enough. It's a matter of accumulating enough timber to stockpile and season it at home. I'm still working on creating a stockpile.
From time to time, I get a load of ironbark or yellow gum, and occasionally I'll head out with my chainsaw to clear a bit of fallen timber from the property. I also use waste bread, which has been converted to 'organic coal' using waste heat after the bake is finished. This waste material burns hot and fast, so it's ideal for putting heat into the bricks at the beginning of the baking session.
No matter what fuel I use, I get good, even heat every time. It's quite possible to take the oven well past 300 degrees celsius, though for what I do, around 250 degrees on the stones is more than enough. I can maintain this temperature all night long with the right management.
Mostly, when the bake is in motion, I average about 40 loaves an hour. It is possible to go faster, but once the oven is full of bread and the bake is underway, there is so much to do that it's hard to put more bread through per hour than this.
The oven is pretty even - it's necessary to run the firebox for a couple of hours before loading the decks, which is called 'soaking' - but when it's up to heat, it's relatively simple to use, and very predictable.
There aren't 'hot spots' as such - you do get a bit more heat at the back of the decks, but when you get a bread rotation system going, it's fairly easy to get a close to perfect bake. Things can come unstuck when an unknown factor such as hotter wood, or a change in the weather, affects the timing of the bake - but after a year of using the Gypsy bakery, I can say that most things come down to experience.
Fuel costs for the oven
Currently, I use about a trailer load of offcuts from the sawmill every three or four bakes. At $30 per load, fuel is costing me about $10 per bake. When I buy seasoned firewood - which is rare - I pay about $120 per trailer load. This timber will do about four to five bakes on average, as it is slightly better quality - though this also varies. So if I have to buy from a timber guy, on average it costs me about $30 - $40 in wood per bake. Still pretty reasonable, given that each bake produces around 300 loaves of bread. I should also mention that I only bake once a week, so I am heating the oven from cold each time. In a typical bakery, one of these ovens would hold some heat overnight, meaning less fuel needed to heat it on a daily basis per bake.
Insulation of the oven
When we designed Luna, weight was a factor - so insulation materials were chosen for their weight. We have used a fair bit of Hebel around the outside of the decks, coupled with some ceramic blanket. If the oven was to be used in a permanent location, it could be built with brick all around the chambers. This would increase the weight and the cost, but would mean that the oven would retain heat better for daily use.
As mentioned earlier, Luna takes 2 to 3 hours to heat to 'soak' from cold. If it is warm at the start, it will be hot in an hour. She has 3 metres of deck space spread between four decks. If I was to have some assistance, and with everything prepared beforehand, she is capable of baking 50 X 750 gram loaves of sourdough per hour. I do a bit less than this on my own, and as yet have no proper coolroom on the trailer, which affects the score a bit.
Luna weighs about 2.2 tonnes all up, as we have had to add more stones to the baffling underneath, as well as extra hebel in the flues to tune the flue gases better. Yes, she has ended up a bit heavier than originally planned, but she is an excellent working oven nonetheless.
The future - for Luna, and the Gypsy
A more refined version of Luna will be offered for sale on this website in the near future. She will have a smaller footprint externally, but have the same capacity. We are also currently designing a range of smaller capacity ovens in the same basic configuration - a one metre version, a 1.5 metre and a two metre version also. These will have some slightly different doors, and will be flued more efficiently. While my oven is fairly even, these future versions will be even moreso, as we have resolved a few unknowns with the experience we have gained so far.
Stay tuned for details of these new ovens, to be known as 'The Artisan Series', in the shop section of this website soon.
I'm still deciding whether I want to bring the Gypsy Woodfired Bakery Experience back out on the road again though. On one hand, it's great to get the baker's craft out there on show in public. On the other, to do this, it will require lots of work and a fair bit more money to either rebuild the trailer or to build a smaller, lighter oven.
For now, the Gypsy stays where she is; she is, first and foremost a tool for teaching and making awesome sourdough bread. If you want to see her in action, come to a workshop!