First Firings

Everything was really wet after the storm so I let everything dry out for a week then did a test burn of a couple wads of newspaper and a chunk of 2x4. Smoke started leaking out of some hairline cracks around the bricks at the top of the dome. After things cooled down I pushed additional mortar into these joints with a grout float. Two days later I fired it again with a slightly larger pile of stove wood (a half dozen pieces) no smoke out of the dome! However, a lot of smoke out the oven door. It seems my flue opening is much to small! I may need to rebuild it, or cut out some material with a grinder sometime in the future.

You can see how small the opening is in the picture. Smoke skirts the edges of the opening and swirls out the front, especially if the wind changes direction to blow from behind the oven.

Day 11: Mud All Over

Two days later, and new bucket of mud has been applied over the whole thing. The flue has arrived and been fitted too! (Looks a it like a steam engine to me.)

Anyway, everything is done just in time as I am going on a 1 week camping trip and a typhoon is coming in a couple days.

When I get back from the trip, my work vacation is over, too.

Day 10: Arch and Flue

The flue opening is the least well documented part of the Forno Bravo plans. I found some proportions of 2:1 of flue to flue opening and followed that. [later I would realize that my flue opening is much to small!]

The flue opening was formed by cutting out segments of the brick arch over the oven vent/landing. I decided on a metal flue, and mounted the flue pipe base directly on top of the flattened top of the flue opening. I spent the rest of the day covering as much of the dome exterior with mortar and filling large gaps with bits of brick. I got about a third of the dome covered before I had used up bucket number two of refractory mortar.

Day 9: More Courses; More Troubles

I started on more courses a day or two later. Everything was going pretty smoothly -- I thought! -- until I noticed that the open ends of the vault were sagging inwards. Luckily the refractory mortar was still plastic and some wedges and props got everything pretty much back in line (or circle). I had to add some squinches to make everything fit correctly.
Messy but virtually invisible -- as this area will be right inside the oven door. I was ready to do my first completely closed ring. It came out slightly eye-shaped, but no worries: I figured I could fix it on the next course. I was now on the last few courses, and the angle of the bricks meant that I needed some more supportive forms.

I also built the side walls of the oven landing/flue arch so that they would have plenty of time to cure hoping to thus avoiding the thrust issue I encountered with the oven opening.

I cut a plywood circle with the jigsaw and marked a bunch of concentric circles for guides. This was propped up in the center of the vault with a scrap of 2x. Wedges laid on the plywood supported the bricks at the correct height.

At this point I fixed the out of roundness issue with two more squinches. (covered with mortar on the right of this image.) A few rings closed the top. I immediately popped out the form and cleaned up the mortar on the inside of the dome. Dome done!

Day 8: Arch Troubles!

It was time to spring the arch for the oven door. I quickly made a ply wood template and cut and laid in the arch bricks. Everything fit perfectly. I pulled the arch support and then trouble struck: the mortar on the piers supporting the oven door arch had not set enough and the thrust from the new arch started spreading the thrust blocks.

Some clamps quickly stopped the movement. At this point I also realized that the new arch could not adequately absorb the forces from the incomplete oven dome rings. More clamps, and some bricks for counterweights helped get me back on track. At the end of the day, I had the oven opening and 4 courses.

I love the look of the oven at this point with the clean interior and the bristle-block exterior. I wish it could stay this way!

Day 7: Helpers!

With the base and floor done, I figured things would go pretty quickly from here. I convinced a couple of friends to come over and help.

I cut two quarter circles of plywood to the diameter of the finished oven dome and used these to true the floor and the dome vault. The great thing about these forms were that they would fit out the oven door so I could use them for all the courses, and they could be positioned wherever I needed them.

Generally this meant at the start of a course and under the brick I was working on. I also used them to check that the arc of the vault was staying true and to make corrections as needed.


With one person cutting bricks and me placing them it did go pretty quickly too a point -- but it ended up taking three times longer than I thought. [9-year-olds can help cut bricks, too!]
I had fabricated wood wedges to the correct angle needed between bricks. I used these a lot on the later courses, but the early courses went together without incident. Once the angle was set correctly on a few bricks in a ring, it was easy to "feel" the right angle on the remaining bricks in that ring.

Day 6: Oven Floor

I cut the ceramic insulating board into the appropriate shapes using a jigsaw. The pieces were glued down with coupe dabs of liquid nails. [Note: Ceramic insulation is nasty stuff and needs to be treated as a hazardous material -- respirator, eye protection, gloves, etc.]

The insulation material loves to soak up water. Before setting the floor bricks in their fireclay-and-sand base, I had to liberally wet the board with water. I had to work quickly with the fireclay mixture as the board soaked the moisture out of it in seconds.

I wasn't too worried about the bricks overhanging a bit as I was planning to cover the entire oven in an oven enclosure. [This later changed, requiring some remedial cutting with a masonry saw on an angle grinder!]