OctoForno

[GianniFocaccia]

Re: OctoForno

Howdy Nate,
I used the classic homebrew recipe using 120 silica sand. The ratio is 1-3-1-1 portland, sand, hydrated lime and fireclay. This made for a smooth, creamy mortar that was a pure joy to use and very sticky. It also cleaned up with a moist rag and if I build another oven I will use the same stuff.

John

[Pompeii Nate]

Re: OctoForno

Hey John,

Since I have never done any kind of masonry work before and have no idea how much of the ingredients to buy, I was wondering if you could tell me. I want to do the homebrew mix but have no idea what quantities to order. I know you gave the ratios of what to use but how much did you use in your build to get the dome completed? I don't want to buy way too much but I also don't want to keep running across town to buy more because I didn't get enough. Any idea how much you used? And I can't remember if I asked this or if you stated it somewhere already but do you remember how many bricks you used?

As always, your information and time (or anybody else's) is greatly appreciated.

Looking forward to see more pics of your build

Nate

[GianniFocaccia]

Re: OctoForno

Nate,
I couldn't tell you how many bricks I used because i didn't go with half-bricks and switch to 1/3 bricks as I neared the top of the dome like most builders do. I purposely started with a narrower brick than most on the first course and staggered each successive course right in the middle of the brick below. I ended up with about 32 bricks per course over 13 courses and a plug instead of the standard 11. Most other builders report using about 200 bricks I think.

For the homebrew, one 50lb bag each of fire clay ($9), hydrated lime ($8), portland ($7) should cover your build. I went through three 50lb bags of silica sand (120) but threw quite a bit away since I didn't cover my dome.
HTH,
John

[Pompeii Nate]

Re: OctoForno

Thanks again John. I figured it would be around 200 bricks but I gotta say I am glad to see that you got by with only one bag of each (excluding the sand). That sounds much better than the $95/bag it would have cost for the high temp mortar from my local supply yard.

thanks!

Nate

[Mike D]

Re: OctoForno

-You end up using a lot more mortar and bricks than you can first imagine. I don't know how many time I have been back to the store to pick up one thing or another. Good luck.

Mike

[Pompeii Nate]

Re: OctoForno

Thanks Mike. I will need all the luck I can get.

Nate

[GianniFocaccia]

Re: OctoForno

Thanks again John. I figured it would be around 200 bricks but I gotta say I am glad to see that you got by with only one bag of each (excluding the sand). That sounds much better than the $95/bag it would have cost for the high temp mortar from my local supply yard.

Yup... I couldn't justify spending that much for a mortar that reportedly didn't perform as well as the homebrew. After three or four gyrations of sand combinations/proportions, I settled on a recipe I really like and would use again. The properties I found beneficial were workability, stickiness, and is non-water-soluable.

I will be happy to report my curing and firing results once I get to it, and am most curious to observe whatever cracking occurs.

John

[Pompeii Nate]

Re: OctoForno

So I noticed in another thread you said: It'll probably take some practice, but I'm sure I can figure out how to do two mortars without tearing my hair out. Thanks again!

Did you end up doing that or just going with the 120 silica sand all the way through? It doesn't seem like it would be that hard to just do 2 different types of sand, one for the smaller joints and one for the larger, outer joints but having not laid a single brick or mixed any mortar myself maybe I am just being overly optimistic. Your thoughts?

[GianniFocaccia]

Re: OctoForno

So I noticed in another thread you said: It'll probably take some practice, but I'm sure I can figure out how to do two mortars without tearing my hair out

Funny you should ask! It turned out to be easier in concept than practice. I started my oven with angled soldiers that left a large gap on the outside. I buttered a 120 silica sand mortar into the inside gap (about 20% of the overall gap) and was pleasantly surprised at how effective this was at securing the bricks. I came behind and backfilled the large outside gaps with a larger grit mortar. After the mortar dried I wiggled some of the soldiers and found that the ones that came loose did so because I hadn't stuffed the mortar into the joint until it was completely filled. There was a space the size of a thumb drive inside each soldier gap. It also didn't help that the mortaring was done in 104F summer heat and that my mortar was way to dry to begin with.

So... I tore them all apart, cut the angles off and laid them in horizontally. What I found out was that gravity helped bond each horizontal brick and that I could build as many courses in a true vertical soldier-like fashion as I wanted.

I also decided I would go with 120 mortar throughout which meant I had to cut each joint to be no larger than 3/16" on the inside and 1/2" on the outside. This single decision probably added 40% of the build time to complete my oven, but now that the dome is done, all I can say is: It is what it is.

What I really learned was to make my mortar wet enough to ooze out of the joint when pressing a new brick into place. I feel this approach resulted in a completely homogeneous, consistent layer of mortar between each brick with no gaps. I'm hoping this will contribute to a lower incidence of dome cracks but only time will tell.

John

[Pompeii Nate]

Re: OctoForno

Once again, thank you John for all the information. I gotta say...some times I get to the point that I feel like I can take on such a project but then I think of something else and I begin to doubt that I will ever have the skills to accomplish something like you have done. thanks for all your help. I will have to find someone else to start bothering with all my questions so as not to burn you out. Thanks!

Nate

[Dino69]

Re: OctoForno

John,

I am really liking the thermal break you show in your pics. At least, so I do not look too dumb, I am hoping that is a thermal break.

I like the insulating firebrick next to the oven floor, but what did you place under the stainless steel? Is it an air gap or maybe a slice of ceramic fiber board? It looks like it would function really well and help save all of that residual heat so many on here use to cook with days later.

Did you use a thermal break after the internal oven arch? So far this seems only one of the problems in designing my oven. The thermal breaks seems tricky for me. Not the concept, but implementing them in a solid way into the arches.

I am really diggin' all the builds on here. You guys really raise the bar for those of us hoping to build at some point in the future.

Thanks,

David

[GianniFocaccia]

Re: OctoForno

Dino,

Thanks for the compliments. Yes, the white-colored insulating firebrick (IFB) is a thermal break designed to keep the firebrick subfloor isolated from the entryway floor bricks. I dropped my soapstone entryway floor design after SCChris reported huge heat losses from his soapstone entryway floor. Once Chip posted pics of his stainless steel entryway, I was hooked, and have my brother fabricating a 16-gauge 316 (restaurant grade) entryway floor as we speak.

Below is my current floor break design. The space between the beveled soapstone and stainless flange is an air gap. The material just just inside the flange is 2" of Insblock insulating board, left over from the top layer of my oven floor insulation.

John

[Gary Mots]

Re: OctoForno

John, I'm a newbie on here, trying to get some info on building an oven, thanks for you and all the guys on here for all the pictures and recommendations. I went completely through your great post, you have done an awesome job on you oven. Thanks again, the info and pictures are going to be invaluable when I get started.

Gary (Valley Center, Ca.)

[GianniFocaccia]

Re: OctoForno

Gary, welcome! If you haven't downloaded the plans yet, check 'em out and remember to post lots of pics.
John

[Dino69]

Re: OctoForno

John,

Soapstone sucks up the heat big time. I have a soapstone masonry heater in my house and it takes up the heat, and holds it, like nothing I have ever seen.

Just the little bit of stainless you have for the break looks good. Nice and clean. The entire entryway will no doubt be killer.

So no thermal break in the arch then? Only on the floor? I guess maybe the vent opening would act as a break of sorts in the arch itself. A big air gap.

Thank you for your time.

David