I've finally started our oven in Costa Rica

[carloswlkr]

Re: I've finally started our oven in Costa Rica

Dino,
Thanks! Yes, the cooking part is great!
I have a single layer on the lower 1/2 of the oven, and double layer on the upper 1/2. I must admit, there were still quite a few coals on Saturday night when I closed off the oven, and the next night, there were still some burning coals under a few inches of ashes when I loaded the oven with green wood (yes, I was careful to keep the wood away from the coals!). So I guess the better test would be to remove coals from the oven and then see how long I can maintain cooking temperatures.
All the best,
c.

[Dino_Pizza]

Re: I've finally started our oven in Costa Rica

Carlos, nice job on your oven. It's great to get to the cooking part isn't it? Do have just 1 layer (1") of blanket on your oven? If so, that is pretty good heat retention you have. The vermicrete layer will make it even better.

Eric: Many (including me who has an aversion to doing anything with concrete if I can avoid it-not really good at it) used just the blanket. 1" of blanket IS equal to 3"-4" of the vermicrete. I've got 3" of FB blanket all around the dome and a 4th layer laying on top. No heat escapes. My oven is being enclosed (out-house style) but if you go with an igloo style, most will then have 1-2" of blanket then the vermicrete mix around it to get it a nice round shape and ready to stucco for creating the igloo enclosure. Good luck on your build.
-Dino

[carloswlkr]

Re: I've finally started our oven in Costa Rica

Thanks for your kind words, Eric. I've been using my oven extensively for the last six months. Unfortunately, work has caught up with me, and the joy of eating pizzas has overtaken my fascination with the construction process... or maybe I'm just feeling lazy about mixing the vermiculite / concrete slop again! but the point is, I've been using my oven with just the ceramic fiber blanket covered with a piece of black construction plastic, and have had no noticeable problems.

To give you an idea of the heat retention I'm getting, I fired the oven up on Saturday night, and had a blazing hot fire going for a few hours. At around 11pm, I closed it off with quite a few coals. The next day, at around 4pm, I baked bread in a 480 degree oven, and at around 9pm, I loaded the oven up with some relatively green coffee wood that I needed to dry out. (aside: Much to my disappointment, the 12 m2 of coffee wood that I recently bought is still quite green, so it takes several hours to get a fire going -- but now I think I've found the solution -- using residual heat to dry a batch of wood out after each session). By the next evening, (48 hours after first starting the oven), the wood was bone dry, and the oven was still registering around 230 degrees.

So I guess my point is... my oven is working just fine with the ceramic fiber blanket. But I still plan on covering it with the vermiculite concrete. Why? because there is still some heat loss... the outside heats up to around 120 degrees... and I'm not so proud of the black plastic look! I suppose I could just cover it in stucco, but I'd rather use up some of the vermiculite that I bought and err on the side of insulation overkill.

Hope this helps!
carlos

[eprante]

Re: I've finally started our oven in Costa Rica

Carlos,

Very nice work on the oven. I love the arched opening and am going to make a very similar design for my oven( soon to start).
A question for you or anyone else that is reading this- is it necessary to do ceramic blanket and 4" of portland/vermiculite? I had been under the impression that the blanket was like the FB board/Portland vermiculite insulating layer, either or. Since I haven't started yet it would be good for me to get this straight.
Eric

[carloswlkr]

Re: I've finally started our oven in Costa Rica

I finally got around to putting on the first layer of insulation on saturday. I did a quick patch job on the few cracks in the oven, which had pretty much stabilized over the last 5 or 6 firings. My ceramic fibre blanket is now on, and held in place with chicken wire. We had another party on Saturday night, and my infrared only reached 110 outside temperature, at the height of the night. The last of the wood was added at around 8pm, and the oven was closed off with just a few coals at 9:30. Twelve hours later, the temperature was 450 floor and dome; another 12 hours later, and it was only down to 250. I imagine those numbers will be slightly higher when I finish the 4" of vermiculite.

Did I mention that I love my oven? ;-)

[Salv B]

Re: I've finally started our oven in Costa Rica

Carlos, Good to see you have things sorted and have done more cooking. I am envious of your door! I paid $50 Australian to have a 2.5 mm stainless piece supplied and cut for me. And it gets very hot.

[carloswlkr]

Re: I've finally started our oven in Costa Rica

Thanks, Salv. I had another cooking session on Sunday, and threw a quick mix of fireclay, portland cement, and lime together to cover up the seams. Sealed off the smoke immediately, and didn't open up again. I might remove it and do a better filling job before I get around to covering it up with the blanket and insulation... or i might not! I'm not so worried any more.

I, too, made bread in the oven this weekend, for the second time. I didn't get to try the first batch, since both loaves went as gifts to friends. But we're enjoying this weekend's batch... I use the same recipe for a multi-grain bread as I use indoors, but it takes 1/2 the time to cook. I also made a slow-cooked osso bucco. Put it in when the oven was down to about 450, and left it overnight. Took it out at 5:30am, and it was amazing.

I also tried out my door for the first time. I don't have a shop or tools to make things myself, but tracked down the guy that makes the pizza peels for our local restaurante supply store. I commissioned him to make my rake and shovel, and gave him a design for the door. He charged me a whopping $35. He had never done anything like it before, but I'm happy with the results. It is filled with loose vermiculite.

all for now!

[Salv B]

Re: I've finally started our oven in Costa Rica

Hi Carlos,

Sorry to hear about the cracks. I am certainly no expert in this area but I did experience a few cracks as well and ended up doing what you intend to do - I filled them from the outside with the high heat mortar I used for the rest of the dome. I then did a thin render coat over the whole dome of the fireclay and portland cement home brew and then put the insulation layers on. I did this after noticing that the cracks would expand during firing and contract back down when cooling down and there weren't any other cracks on subsequent firings. In the end as long as the dome was likely to stay together I was happy with the outcome. Best of luck sorting this out - I'm sure it's just a small glitch.

[carloswlkr]

Re: I've finally started our oven in Costa Rica

Thanks, Jorge. I'm not really interested in using epoxies... I'll probably just go with the refractory mortar I used to build the oven.

[unomauser]

Re: I've finally started our oven in Costa Rica

Carlos,
Try the link below, it contains great inf on high temperatures sealants.
Cheers
Jorge

High Temperature Adhesives and Epoxies, Ceramics, Insulation, Epoxies and Epoxy

[Dutchoven]

Re: I've finally started our oven in Costa Rica

Carlos
I am so sorry to hear about this. I am not certain really how you should go about reparing it...I think you need to since you can see the inside of the oven. I might suggest using just a slurry of fireclay and sand and sort of let is ooze into the crack from the outside...if it is just fireclay it does not really harden until it is fired which means you could probably fire it up in the next day or two and it will harden as it expands?...in any event I would mark it across the crack and fire good and hot a few more times then you can see if there is any other movement and give it a chance to stabilize before you repair it...maybe we will get some other opinions
I hope this helps! Good luck!
Best
Dutch

[unomauser]

Re: How worried should I be?

OK, how worried should I be?

I uncovered my oven tonight and started another fire for a four pizza session. When I walked around the oven, I discovered a new, somewhat worrying crack. I can see the inside of the dome, and smoke occasionally escapes. It goes all the way up from the soldier course, to the top of the dome. Should I be worried? Should I try to fill the crack from the inside and out? I still haven't applied my insulating layers, so a little more work on the dome won't hurt. Any suggestions?

Thanks.

ps. that's a penny in the first and third pictures to show some scale.

Carlos,
Congratulations with your oven it's a nice one. Unfortunately cracks develop on almost any refractuary material, you may try to use a high temperature putty to fill the cracks. Try this link hope you find a solution for your problem .
http://www.cotronics.com/vo/cotr/rm_putties.htmbelowand
Good luck.
Jorge

[carloswlkr]

How worried should I be?

OK, how worried should I be?

I uncovered my oven tonight and started another fire for a four pizza session. When I walked around the oven, I discovered a new, somewhat worrying crack. I can see the inside of the dome, and smoke occasionally escapes. It goes all the way up from the soldier course, to the top of the dome. Should I be worried? Should I try to fill the crack from the inside and out? I still haven't applied my insulating layers, so a little more work on the dome won't hurt. Any suggestions?

Thanks.

ps. that's a penny in the first and third pictures to show some scale.

[carloswlkr]

Re: I've finally started our oven in Costa Rica

Lucky for me, all the tapered bricks cost the same as the standard firebrick... around $1.50! I would hate to have to cut them all on a taper lengthwise with the tools I had at hand!

[Salv B]

Re: I've finally started our oven in Costa Rica

Hey Carlos,

Congratulations on getting to your first pizzas. Everything looks great and you obviously got the hang of it right away - 16 pizzas - not bad! I haven't been game to do that many yet.