36' low dome neapolitan style

[MarvinG]

I suspect it is because my door seals quite well and my door is quite thick, so it effectively blocks the chimney throat too. While some heat must be lost with convection, I do not see this as a major problem. A flue baffle won't hurt, of course, but it's one more moving part so more to go wrong in my view.

True, great Idea!!!
I will make the door quite thick then too!
You know, since I go directly in the chimney of the house, which ends at a hight of about 5 meters there is constant draw. But like this it's basically solved. And yes, I of course am not keen on making a flue baffle. Believe me, connecting my home-made double walled insulation pipe was painful enough. this will not be touched again! ;-)
But it was worth it - it cost me in total about 50$

[MarkJerling]

One thing: Over my furnace insulation I added conventional fibreglass insulation, a thick layer. And, over that foil. (No-one here uses foil under the plaster, apparently it slows the drying time of the wet oven construction.) The advantage of lots of insulation is that my oven holds it's heat very well and the outside plaster render remains cold. I have one small area that feels slightly warm, so I suspect I must have a tiny gap there in the insulation, but the rest of it stays cold outside even though it can be 600degC + inside.

[MarvinG]

Interesting. I don't plan to use the foil, neither the gals-fibres

Today I have received the 2nd approval from a very knowledged gas fitter who visited the place. Looks all good. He even said burning wood next to it would not be an issue at all. However I will probably still not do that due to the "mess" it creates and it still ads a potential risk.
Since the gas fitter was here we had the flame running quite a bit for a while - and then - I found a first little crack. I guess it's not very relevant and because I did not create any bridge between the arches?
So the crack is in the outer and then in the inner arch half way so far. But the Oven is still not dried. Today it was the 4th small fire - still waiting for my infrared tool.

Regarding the insulation. On the uppoer 2/3 of the oven I will have 3 inch of ceramic board, below 2 inch. Then I will add around 2 inch of Perlit-cement. I assume it will be good enough. The oven thickness (bricks) is 5 inch.

Here a picture of the cracks:

[MarkJerling]

Go slow with the heat. Small cracks are almost inevitable. I have three small cracks in the dome but those occurred with the first few fires. Nothing has moved since.

[MarvinG]

Good Morning!

That Is how the oven now looks:


I have a few question with the next steps.
I bought red tiles, will crack them and then place as the last layer. Before there will be plenty of Cement/Perliti Mix.



First: The Ceramic planket sucks up all the water from the cement mix, correct? I guess that is not an issue?!
When I have poured the cement - what layer shall I make in between the Mazaika and the cement. I assume I need some in between layer to make the dome smooth? I have never done mozaika - is anyone experienced what materials to use?
It shall look like that in the end (more or less)


Another question which has come up. I bought this Temp. sensor.



On what hight of the side shall I place it? Anything that can go wrong when I drill into the oven and put it? 30cm is a bit too long, can i cut it or does it measure the temp on the very end? Or do I destroy its ability when I cut it?

Thanks

[MarkJerling]

30cm is a bit too long, can i cut it or does it measure the temp on the very end? Or do I destroy its ability when I cut it?

Looking good. Don't cut it, you'll stuff it.

[MarvinG]

Hi Guys

I have continues and finished the perlcrete part.
So the final shape is achieved. Finally!!!

How do you usually drill a whole for the thermometer. I mean - I have a 10mm drill which is 40cm long - but the thermometer is only about 4mm thick. Do you stuff soeehing in the "too big hole then"?
Since I would like to have these red tiles on top. Do you usually buy a normal stucco and put black color in it - or how does that go?
Do you seal the gaps of the mosaics in the end after gluing the mosaics? Sorry - I have never done anything like it and was not too successful with the search in the forum. The stucco will be about 8mm thick - so not too thick. But I don't really have more room unfortunately. Do you buy stucco or also do your homebrew?

And a final question. It's an indoor oven - so I only need to care about the humidity getting out. Shall I start curing when I have applied 9/10 of the mosaics - so the humidity can leave easier I assume?

[Kvanbael]

A mosaic finish needs a strong even surface to be attached to. That would be the function of your stucco render (not sure if stucco is the right term if it isn’t the final layer). Furthermore it will add some crack strength to the perlite. The mosaic tiles are then attached with a tile “glue” (also a concrete based powder to mix with water). And the space in between the tiles is filled with “grout”, which comes in many colors. I suggest you do some
youtube searches on mosaic tiles.

[MarvinG]

perfect! Thanks a lot Kvanbael . This helped a lot through the Adhesive/Mortar jungle! :-)

[david s]

It is better to do the drying fires after the perlcrete or vermicrete insulation layer, but before the stucco layer. This allows the moisture to escape more easily.

When fitting a thermometer probe I like to use a stainless tube 8 mm outside diameter into which you fit the thermometer probe. This protects the thermometer probe.Insert it so the end of the sheath and probe are flush with the inside of the oven wall around half way up the dome.

[MarvinG]

Thanks for your Post david s

I assume I was too quick then.
Today I made my own stucco with 4:2:1/2 (sand, cement, lime) I used masonry and portland cement 50/50. I applied about 5-8mm I assume.
I applied this only one day after I have completed the perlcrete - so yeah, all the humidity is really inside now. Hope this gives it good strength, but curing will not be so easy then.

Or shall I remove it in some parts so the oven can breath out there?

I plan to let it rest for a week now - and then slowly start firing it up again.( I did a few fires before the Perlcrete after the bricks rested for about 2 weeks). I will also wait with the mosaics until then, because this layer seals even more. Hopefully the humidity does not become a problem...

I changed the shape slightly. In the morning when I looked at the picture from yesterday I did not like it too much. with the extension towards the pipe it looks better I think.

Great, thanks for the hint with the stainless steel pipe to put the thermometer through! Is it a problem if the probe comes out a few centimeters into the oven? The reason why I ask: I would like to have the thermometer flat on the outside between the mosaics. But the probe is longer than the oven is thick. At least in some parts. If I drill not perfectly 90° to the wall it might be perfect, but I dont know exactly how thick the oven is in all places... :/

[david s]

Yes it is difficult working out the length of the hole. I drill at an angle to make it longer.Better to have it protrude from the outside than inside as it will get in the way and be subject to damage if it sticks out too far into the oven interior. Go slow with your drying fires. You can do it too fast and risk damage but you can never do it too slow. If you see visible steam back off.

[MarvinG]

Here a quick update after this long period of time. Meanwhile I have finished the top layer and had it up to 300° Celsius.
I assume although I was heating it for about 10 days, it still has humidity inside. Since I put the cement right on top of the perlite layer, I made it difficult to escape. What I saw when I heated it up was this:

Any thoughts?





Another thing I have noticed. Inside the oven it smells quite a bit, I guess that is the smell of concrete which is curing? How about your ovens?

When I heated it up to 300, it got its probably final crack, basically above the flame, vertically up to 2/3 of the come. Half between the bricks, some bricks even cracked through. I guess that's how the oven feels comfy now. :-)

Apart from that I was super surprised about the heat storage. When I have it up to 300°, I have about 180 the next day (with an improvised door). Now I have a steel door with 10cm of insulation in between. So I'm curious how it will store it. On the outside of the oven it does not even get handwarm. It's only the floor which gets about 50° I assume.

Here a picture from the oven door in the process, before I stuffed it with ceramic fibre board.



Now the oven looks like this. What do you think?






Very soon we will finally start baking :-)


Cheers, Marvin

[Kvanbael]

Hey Marvin, it looks stunningly great. Red mosaic turned really well.

When will the business open?

[MarvinG]

Thank you very much! It was "quite a bit of work". We will start baking very soon - today we were testing different food suppliers, as soon as the things are finalized we'll start. Roughly 2 weeks