Mini Forno: The Homebrew mix experiment

[Saovicente]

I wanted an oven without breaking the bank and I found the homebrew mix to be a tempting solution, but I was hesitating, because if it were to fail, I would lose quite a few $$$, time and effort.

I set out to experiment with the homebrew mix by creating a miniature oven to test the durability of the mix properties and its endurance thru multiple firings, cooking, etc.

I wanted to keep it simple and straight forward without much fuss. I mixed the 3.1.1.1 - added a good amount of fibers from a brown rope that was taking up space in my shed.

I went through the drying process with 3mil bags over the mix for a few days, then a few more days with a 100W bulb, then 500w ( the bulbs worked great, I have burn marks on my wrist to prove it)

After the bulbs I started with slow fires to finish the drying process ( after reading so many threads on the various steps of building an oven – I had not realized how tedious the drying process can be). You know the rest.....

The homebrew mix is a success. Onward to the Gigantic Barrel Forno, which will have steel needless and more brown rope added to the mix.

Below are a few pics on my Mini Forno in action. The Oven has a few stress fractures due to my impatience at the end mark (always the end) in drying it and possibly from moving it three times. ( It kept getting heavier with each move)

A special thanks to michelevit for his inspiration in creating a brickless oven on a shoestring budget. As for the way the economy is these days, every penny counts,

[Saovicente]

Re: Mini Forno: The Homebrew mix experiment

The rest of the pictures.





Please fee free to ask any questions and/or add suggestions.

Thanks
Sandro

[cobblerdave]

Re: Mini Forno: The Homebrew mix experiment

G'day
That is a very cool little oven.... But why a barrel oven and not a dome?
( this is not a leading question either so I can give you my views I'd like to know)
Regards dave

[Saovicente]

Re: Mini Forno: The Homebrew mix experiment

Thanks Dave

Why barrel?
1) I wanted a versatile, spacious oven I could tweak to perform various tasks (Pizza, Bread, Roasting, Baking, etc.) and keep very good heat retention throughout a few days. As a few have written here; of having the ability to quickly bring a barrel oven up to temperature even after days of nonuse. I do not mind spending the initial 1 ? to 2 hours to get it to pizza like temperature (Goal is 60to75mn) and then cruise thru a few days of making this and that with a few pieces of seasoned wood..
2) The look of the exterior, interior space: The linear line with the curved arch provides for more of an artistic pizzazz.

Sincerely,
Sandro

[cobblerdave]

Re: Mini Forno: The Homebrew mix experiment

G'day
You could probably get that heating time down.
Mines a 110 mm 4 1/2 in brick dome and its 1 1/2 hour to 2 hour to pizza heat.
A thinner caste shell say 50 mm is about 3/4 to 1 hr to pizza heat.
Yours should be roughly in the middle. ( so many other variables!)
Remember though tunnel ovens usually have a lot more mass due to the mass of the buttressing. You are right though its easier to bring a warm oven up to temp than a cold one.
Thanks for the reply
Regards dave

[david s]

Re: Mini Forno: The Homebrew mix experiment

You haven't mentioned how big you intend making your oven, but the larger the chamber the more fuel will be consumed. For a small oven because you use such little fuel the reheating the following day is hardly an issue, for a large oven it is. This means that if you wanted to cook a couple of pizzas one night but had not planned on cooking anything the next day, you'd probably think twice about burning a large amount of fuel for those two pizzas. Maybe you should keep your small experimental oven so you can use it for this purpose.

[Saovicente]

Re: Mini Forno: The Homebrew mix experiment

Dave,
I appreciate the reply. I have read many threads on the different ways of configuring a barrel oven to maximize it's efficiency and minimize the time spent firing it plus retaining the heat.
Based on the various threads I have read ( so many good ones throughout the last few years (Barrel and Igloo)), I have taken a bit of this and that and will add of the learned knowledge from this great site and incorporate all into my build plus a thing or too from my knowledge base.

I will be starting a new thread in the next two weeks to chronicle my build and I am looking towards to some feedback as I progress forward.

I thank you,

Sandro

[Saovicente]

Re: Mini Forno: The Homebrew mix experiment

Maybe you should keep your small experimental oven so you can use it for this purpose.

David,

As always I appreciate the input ( after all, you gave me the ideal of adding stainless steel needles ( To which I have purchased) to the mix.

As for using the experimental for mini pizza's and such: Unfortunately, I have given it to my beauty as a gift to compensate for Valentines day. It has been deemed "cute", so it will be finished with a chimney and destined for ???.

As for the dimensions of the barrel oven. It will be 36" x 48". My plan is to make it into 5 pieces (L/R Walls, Back and Front, Split arch in two)
The hearth firebricks will be within the walls of the oven. The walls are to be 9.5", but I will add 2.5" to compensate for the thickness of the firebricks. The opening will be 20"W, 12"H, arch should be about 19"H.

Any suggestions will be appreciated.

Thank you,

Sandro

[david s]

Re: Mini Forno: The Homebrew mix experiment

Sandro,
I suggest you remove your castings from their moulds after a day, then wrap them in plastic to cure for a week, then let them dry in the sun for three weeks before using them to build with.

[Saovicente]

Re: Mini Forno: The Homebrew mix experiment

Gents,

It has been a few weeks playing with the Mini. It fires up nicely (except on windy days), and it maintains its temperatures for a few cooking cycles (mini everything).


I have begun the big boy project. Will create a new thread in the near future as I progress through the build.

[deejayoh]

Re: Mini Forno: The Homebrew mix experiment

You are planning on building an entire oven using the homebrew mortar recipe? That recipe is for mortar, not cast refractory. I am surprised I am the first to comment on this. Mortar is not a structural material. I am no expert, but would guess that a full sized oven will fail pretty quickly over the repeated heating and cooling cycles to which it will be exposed - no matter how much "brown rope" you add to the mix.

What you want is castable refractory aka ciment fondu/calcium aluminate cement.

[david s]

Re: Mini Forno: The Homebrew mix experiment

The jury is out over how long a home brew cast wil last, but there are enough who report it works ok. Two in my local area alone and they're two years old.Homebrew is way cheaper and easier to work with.using a sand mould you can build one in a weekend. So it's very cheap and fast.to build with no guarantees of longevity. Sounds attractive for a home builder to me.

[wotavidone]

Re: Mini Forno: The Homebrew mix experiment

You are planning on building an entire oven using the homebrew mortar recipe? That recipe is for mortar, not cast refractory. I am surprised I am the first to comment on this. Mortar is not a structural material. I am no expert, but would guess that a full sized oven will fail pretty quickly over the repeated heating and cooling cycles to which it will be exposed - no matter how much "brown rope" you add to the mix.

What you want is castable refractory aka ciment fondu/calcium aluminate cement.

I'm surprised that, having been around long enough to post more than one thousand time, you haven't come across this thread:

http://www.fornobravo.com/forum/f43/...oven-9380.html

It's been done before and, while I agree that the home brew mortar in no way meets the accepted criteria for a true refractory, the brickless oven on a shoestring has lasted well according to michelevit.
Let's face it, its sort of adobe (sand and clay) with some stronger binders added. I know the portland can be expected to break down, but that still leaves the lime and clay.

I'm slowly getting around to doing one myself, just to see how it goes. My plan is to go a little shorter on the Portland cement and a little longer on the lime.
I always thought david s was being pedantic (sorry dave) with regard to using stainless steel reinforcing, but having done some further reading, mine will have either no reinforcing or it will be stainless steel, depending how easy the stainless is to come by.

[deejayoh]

Re: Mini Forno: The Homebrew mix experiment

I do know about that thread. That builder used a rebar frame which is not the same approach being discussed here. I don't see it as the same approach anyway. And there are many more examples of castable ovens successfully built out of refractory cement than homebrew, if you want to cite evidence points. But my main point is that mortar is not a structural material, nor is it meant to be.

Mortar is a very different animal than concrete. Concrete is designed to be used in thicker applications and to reach very high strengths. It achieves its durability through brute force. Mortar is also designed to be durable but achieves its goal through finesse. Its strengths are quite low compared with concrete and it is never used in thick applications. - See more at: What is Mortar?

You can build an oven out of a pile of elephant manure and clay, I guess. Up to the builder. But the conversation deserves an accurate assessment of the appropriateness of the material. Personally, if I was going to go to all the trouble of building forms to build a cast oven, I would spend the couple hundred extra to get the right material for the job. But that is just me.

[wotavidone]

Re: Mini Forno: The Homebrew mix experiment

It is arguable that the FB Homebrew mortar isn't really mortar either, as mortar is defined by the average bricklayer.

Ordinary mortar, here in OZ at least, is either 3:1 sand:cement, or 3:0.5:0.5 sand:cement:lime. i.e. quite low strength.

With the homebrew being 3:1:1:1 it is, as pointed out by many a masonry expert on this site, far stronger than traditional mortar, even if the hydrated portland cement loses its chemically ccombined water.

Anyway, screw the science, many have used it and swear by it and if it fails little is lost -as davids points out, maybe a wekends work.

Good onya if you would spend the extra few hundred bucks, the original poster stated up front that he was looking to save as much as he could.

A point of order for anyone who does decide to spring for ciment fondu - beware mixing it with lime, apparently this accelerates the set, making it important to place it quickly.