42" Pompeii Oven in Jamaica

[wthwaites]

Read the curing thread.
Start here
https://community.fornobravo.com/for...curing#post833

Thank you!

[david s]

Read the curing thread.
Start here
https://community.fornobravo.com/for...curing#post833

[wthwaites]

9 days is a good target for the drying fires. Take it very slow as Mike said. I always advise using the charcoal method for the first couple or so days. Adding the stucco will slow down the drying process somewhat. But, If your vents are installed correctly (I saw one on the lower section of your dome) you will have protection against the stucco cracking due to steam pressure imo. One of the david s tips is to place a clear plastic over the oven to test for steam/mositure escaping during the drying stage. So, place a clear plastic bag over your upper vent. If it fogs up there is still moisture that needs to be driven out before ramping up to the larger fires.

What is the charcoal method for curing? The FB guide advised not to use coal in the oven, so I thought that using coal was not recommended.
I do have access to lump charcoal (Logwood), so it can be done with ease. Can you provide some details on this method?

[SableSprings]

Sorry Wthwaites, I missed your addition of the venting pipes in your dome. As Gulf noted that should keep any steam pressure/escape from damaging the render. Glad to hear you're taking it very slow on the cure.

...and here's to a fabulous 2021

[wthwaites]

I have three 1/2" vents installed along the lower section of the dome (one on each side + one at the back) and a fourth at the top of the dome behind the chimney out of sight when facing the oven.
I'll certainly try the plastic bag tip!

Happy New Year!

[Gulf]

9 days is a good target for the drying fires. Take it very slow as Mike said. I always advise using the charcoal method for the first couple or so days. Adding the stucco will slow down the drying process somewhat. But, If your vents are installed correctly (I saw one on the lower section of your dome) you will have protection against the stucco cracking due to steam pressure imo. One of the david s tips is to place a clear plastic over the oven to test for steam/mositure escaping during the drying stage. So, place a clear plastic bag over your upper vent. If it fogs up there is still moisture that needs to be driven out before ramping up to the larger fires.

[wthwaites]

Normally we suggest doing your curing fires before you apply the finishing stucco coat. The escaping steam during the curing process wi!! Most likely crack the outside render. Leave an area on the top insulation if you can and do the curing before completing the outside of simply accept that you will probably need to recoat the outer shell. I really do like the squirrel tail vent design, looks great. If you don't choose to cure before completing the render, go VERY slow with the curing process.

My intention was to do slow cure fires over a period of at least 9 days. But, I thought that the vent pipes that was suggested to be installed at the sides and top would prevent cracking. No?

[SableSprings]

Normally we suggest doing your curing fires before you apply the finishing stucco coat. The escaping steam during the curing process wi!! Most likely crack the outside render. Leave an area on the top insulation if you can and do the curing before completing the outside of simply accept that you will probably need to recoat the outer shell. I really do like the squirrel tail vent design, looks great. If you don't choose to cure before completing the render, go VERY slow with the curing process.

[wthwaites]

Approaching the end; almost there! Some pics of progress.
Just applying the finishing coat of stucco (still working out the color) and then installing the granite countertop landing.

[wthwaites]

Thank you for the tip!

[SableSprings]

No, I did not. I don't think vermicrete is available. Everybody I ask doesn't know what that is.
I thought that perlite used for gardening was not a good option? Isn't the perlite used for concrete blocks a different type?

Perlite for construction often is coated so it flows better into spaces. That coating makes it more difficult to mix with cement, that's why we point people towards the agricultural perlite which is not coated. I used perlite for both my base and covering insulation and it works very well. Pumice should be available and would be an acceptable substitute. Remember that vermicrete & perlcrete are terms used for the insulating mixes we make & use and are not a product you can buy. You need to specifically ask for vermiculite or perlite...those are available. That may be why you are having trouble finding either one.

[wthwaites]

Have you tried hydroponic suppliers? Either vermiculite or perlite or a combination of the two work ok.

No, I did not. I don't think vermicrete is available. Everybody I ask doesn't know what that is.
I thought that perlite used for gardening was not a good option? Isn't the perlite used for concrete blocks a different type?

[david s]

Have you tried hydroponic suppliers? Either vermiculite or perlite or a combination of the two work ok.

[wthwaites]

Thanks.
I couldn't find vermicrete to do that mix. Some materials are hard to find here in Jamaica - even hydrated lime seems to be scarce; can't find it anywhere. However, its likely that I will build more ovens in the future so hopefully I can source then and try that way in the future builds!
The render seems to be pretty solid so far and wasn't too hard to apply since I've been taking my time - 1/4" layers at a time. I also believe that the chicken wire mesh helped a lot with the first layer.

[david s]

The lime makes the mix more workable, making application far easier. It also makes the resulting hardened render slightly flexible and also imparts a self healing crack quality. All these are pretty important. IMO. Most commercially blended render mixes contain lime as well as a waterproofing agent that makes the render partially waterproof, repelling water from entry, but maintaining the ability to breathe.

I find that rendering directly over the blanket extremely difficult because it is lumpy and springy. I always apply a 35 mm thick 10:1 vermicrete mix over the blanket which sets up a firm enough substrate to apply the render on to as well as evening out all the lumps and bumps of the blanket.