Buiding of a 60cm(24'') homebrew oven (NL). Vcrete question.

[Matthijs]

That makes sense.... my firebricks are 5 cm thick

[Matthijs]

Had my first trail run pizza today! Heated up the oven with 5 kg wood. to ~400 dgr C (@18:00) meanwhile cobbled together a pizza.(nothing fancy).
I do not have pizza tools yet, (no pizza peel) quite a challenge to get it on the oven floor, I can tell you. had to rebuid in the oven

The result was not good looking. But it taste fine.

And got my first real pizza oven blister, also.


Analytical info at 21:00 top of dome:280 C, Floor: 240 C Door closed, wood still glowing.)
7:00 Top of dome 100°C, Floor 90°C (door closed)

[Kris S]

Looking good!

What type of sand did you use in the end for your dome? I see there are different sizes: white sand 0 - 2 mm, or 'chape sand' 0 - 4 mm.

I would think 0 - 4 mm would be better because a bigger array of particle sizes would make a stronger mix?

[Matthijs]

Kris S I used "Metselaars zand" This was 0-3 mm.

I have a small 'issue' with my flue.... So for the flue pipe stucco I followed the idea of David S. Where he leaves some room for expansion of the metal flue pipe so it will not break the concrete/stucco.
So around the Flue pipe i packed two layers of cardboard (~5 mm) then some chicken wire (to fixate the stucco) and sticked approx. 1 cm / 2 cm of stucco.

The Idea was to remove the cardboard if the stucco / concrete is cured. Than fill the void with vermiculite or perlite. But ..... this does not work The Cardboard is stuck between the flue and stucco.

Did someone had the same? How did you fixed it? Would it be an option just to fire up the oven and see what the cardboard does?

[david s]

I wrap some plastic around the cardboard for easier removal, but you should still be able to dig it out. High temperature silicon is a better material to fill the gap than vermicrete, as rain tends to run down the pipe and you want a decent seal there, but vermicrete should still work ok.

Actually the last one I did I did not wrap plastic around the cardboard, but used masking tape to hold the cardboard in place and brushed a little oil around it to act as a release agent.

[Matthijs]

Thanks David S. Will try to remove the cardboard somehow. Fill the void AND close the gap with the high temp silicon. (Your advise is priceless.....)

Another question:

I added one layer of 4:1:1 (sandortland:lime) + additive for sealing. So it should be a bit water proof.......
Now I would like to use broken tiles to 'Mosaic' the dome. Would this stucco mixture also suitable as to stick the tiles to the dome? (with some extra additive) for stickiness and elasticity or is there another recipe to "Glue" the tiles?

[david s]

You should paint the stucco with a primer additive prior to tiling as you would for any normal tiling job.The stucco is normally done in a couple of layers although I usually just do it in one, to save time, about 12mm thick. Probably give it two coats of sealer. Also make sure you use a good quality outdoor tile adhesive. I presume you did the drying fires prior to the stucco.

[Matthijs]

Had to redo the concrete / stucco around the flue. I could not get the cardboard removed. I rebuild it and I followed David's advise. and tried release agent (oil). Hope it will remove.

If the material around the flue pipe is removed there will be a void (for expansion). What do you think:

Would it be advised to fill it with perlite OR with 1:10 Portland/perlite OR just keep it empty?

I will close the top of the gap with a Heat resistent silicone (that will be very hard (not flexible) if dried)

[Kris S]

My guess would be it doesn't really matter because the high temp sillicone already keeps the rain out, which is your primary concern.
I don't see a big difference between keeping the gap empty or filling it with 1/10 cement/perlite. Maybe over time some perlite could come loose because of the expanding/shrinking cycles of the pipe, and maybe this could crumble and fall down the vent gallery onto the firebricks? not a big deal probably?

[Kris S]

Also, could you tell what breather cap / valve you used, and where you got it from?

[sergetania]

I got a piece of copper pipe and a cap from a hardware store for a few bucks, drilled a couple of holes in the pipe and soldered the cap over the portion of the pipe with holes. Basically, you want to let the steam out and protect it from the rain.

[Matthijs]

Thanks sergetania. Indeed Kris S And the Cap isn't even soldered.

[Matthijs]

I 'mosaiced' the dome (and the pipe). Quite happy with the result. The tiles needs (washing (filling the gaps beween the tiles)) The plan is to use a dark gray filling mortar to create some contrast.

The gap (fluepipe/ concrete) is covered with a temp resistant. I Hope the temperature will not rise to much and causes cracks in the mosaic. The weak spot is the front of the flue pipe. Lets see what happen if I light the thing.

[Kris S]

Nicely done!

Are you gonna use a special kind of 'waterproof' mortar to fill the joints?
I'm really curious as how rainproof you can make the oven because igloos are much prettier than enclosed ovens.

Is your oven already partially protected, as in built next to, or close by, your house?

Other question: how deep is your flue gallery? I see you also tried to save space and use the dome wall as back of the flue gallery.