Brick and clay pot hybrid

[david s]

Ok, last post to bring us up to current. For a chimney I wanted to vent to the rear, this way I can pull the oven under the pergola without fear of setting it on fire. After considering several alternatives, I settled on a 6” flexible aluminum vent tube. Knowing it may/will erode, I covered the whole thing with refractory mix supported by hardware cloth- and then pearlcrete. My hope is that if/when the aluminum erodes the concrete will remain.
Questions? Comments? Criticism?

Not quite sure how you have arranged the flue, but if you have abandoned the front flue design, blocked it off and now have the flue at the rear of the oven chamber you will not get good circulation of the fire. This is an updraft system and the flames will jump straight to the flue rather than circulating in the oven with a front flue which is a cross draft design.
On the other hand ignore this caution if you have retained the front flue and tracked the pipe over the top of the dome to the rear. We call this a squirrel tail design which retains the benefit of the cross flow draft with good circulation.

[PsychDoc]

David- I defiantly will not ignore your words of wisdom. I did go squirrel tail. The pearlcrete does a good job of concealing the shape.

Quick question- after completing the pearlcrete insulation should I move to drying fires or stucco first? Also- can I place decorative tile “in” the stucco or do I need another layer of ¿mastic

[david s]

All good with the squirrel tail. Because vermicrete or perlcrete contains so much free water (around 1/3 of the volume is water and about 1/2 of that is taken up by the hydration process), leaving a large amount to eliminate, then it’s best to get rid of most of it before rendering over it. An excess of moisture can make the stuff swell and crack even to the extent of cracking the outer render over it. At this stage you are no doubt getting excited and want to crack on and get the thing operating. It is more prudent however to take your time and weather permitting, allow sun and wind do much of the drying. A week of drying is pretty good and a cheap garden moisture meter can also be of assistance.

[PsychDoc]

Wanting to crack on indeed- I have been so slow with the application or pearlcrete and it’s plenty dry in Southern California so I expect it is getting close on the natural elimination of moisture- so maybe some small slow curing fires before ‘rendering’? And is Portland and sand a proper render?

[david s]

The addition of hydrated lime is beneficial in that it increases workability, elasticity and imparts some crack resistance with self healing properties. 4:1:1 is pretty good , but a proprietary render is probably a similar recipe with the addition of “polymer modified” goodies that impart some partial waterproofing qualities.

[PsychDoc]

The obligatory “first fire” pic.

Question- during this heating the outside of the pcrete was ambient temp- all but one spot at top center of the dome- next to the chimney- it felt warm/hot- is this where moisture found its way out? I’ll try a mirror on there tonight. Also I’ll get a pic of the completed dome.

[PsychDoc]

Red arrow indicates hot spot mentioned above

[PsychDoc]

Apologies for anyone interested in this build- the oven has been used several times with moderate success. Last weekend I finally put a scratch coat over the thing. Now time to finish...
I have discovered that I am slow with the stucco- so my questions-
Best material for top coat? I used “quikrete” for the base coat.
I think my pace will mean going one ‘section’ at a time- but complete the same day. Any issues with that? I want to ‘float’ the whole thing to make it smooth-ish.
i will try to add a pic

[PsychDoc]

[wotavidone]

Never mind the oven. Ovens are a dime dozen. Is that a teardrop trailer in the background? Mine is nearly finished.

[PsychDoc]

http://www.tnttt.com/viewtopic.php?f...3547&start=105

[wotavidone]

Well there ya go. Mine is this one:
http://www.tnttt.com/viewtopic.php?f...t=180#p1268670