Go Back   Forno Bravo Forum: The Wood-Fired Oven Community > Pizza Oven Design and Installation > Getting Started

Like Tree12Likes

Reply
 
LinkBack Thread Tools Display Modes
  #161  
Old 05-06-2013, 05:00 AM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,787
Default Re: Structural Slab for new WFO

The other reason you have lots of cracks is that your first fire was kept going most of the day. I suggest you read the curing thread. The temperature ramp up should be done slowly. The vermicrete layer does not matter that much but you don't want to stress the refractory castings. The top of your dome will dry first while the base will still be wet. This creates an enormous difference in temperature between the two which in turn means an enormous difference in expansion of the material which can lead to cracking. Because you have wet vermicrete sitting directly against the hot refractory then steam will be produced easily. Folk who use blanket have a buffer which prevents the vermicrete getting too hot too soon.
Reply With Quote
  #162  
Old 05-06-2013, 05:35 AM
Master Builder
 
Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Structural Slab for new WFO

Thank you for your observations. I have a couple of questions maybe you can fill me in on.

1) What is the history of pericrete--i.e. who started recommending using it?
2) Are there any commercial oven manufacturers who use pericrete in their product that is sold?

A couple things about me--you probably know by now, that I am not a patient person, but I think that I can produce quality products--not necessarily WFO's--but in the other things that I do.

I think that this design is flawed--because there is nothing that will absorb the expansion of the refractory when pericrete is in direct contact. Please correct me if I am wrong!

The render coat that I did, was relatively thin--approximately 9-12 mm thick on the dome itself, but it was rock hard. It takes a lot of pressure to make cracks in that!

I really do not care of the pericrete cracked now in initial firing--or the render either.. Yes it can be covered again. But when the oven is "dry", refractory still expands when heated--and the same situation still would exist. Nothing to take up for the expansion.. That is what I am concerned about! I do not want to be rendering over and over until the cows come home.

A few people around here are interested in WFO's like mine, but I told them--I am not interested in selling anything that I do "Until" I get the bugs worked out!
And if you make more than one, you can't be waiting around for pericrete to dry out! So looks like trash that idea altogether.

I know that you have made several ovens, I do not know if you have sold any to other people... I would rather give them away for free than to sell one and get continuous call backs because of avoidable design flaws. Just not worth it. In house building, I try to avoid bad designs OR if it is an architects' project, I alert them to what I see as potential problems. Then, I am half "off the hook" if something does go wrong.

I noticed when firing, that the top of the oven "pericrete" felt very warm to the touch--also areas where cracks appeared were hotter.. Da--direct path to refractory! Most of the other areas including the chimney were rather cool. The IR thermometer did not give readings over 200C anytime during the day... Most of the readings were in the mid to upper 100 range. Hottest area was the top of the transition--where smoke and heat exited before going out the chimney. Never was the fire anything near roaring..usually flamed up and then went back to smoldering embers when the easily combustible fuel was spent.

Cannot see any damage to refractory that was poured in January and able to withstand temps to 1450 deg. C. Really thought that it was a slow burn! Sorry if I sound Irish!

Anyway, yesterday was my only day off for a while--have to jerryrig some decent cover so the oven does not get soaked! Thanks again!
Reply With Quote
  #163  
Old 05-06-2013, 05:41 PM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,787
Default Re: Structural Slab for new WFO

Perlcrete directly against the refractory does work, but it needs to be dried out. See my PM
Reply With Quote
  #164  
Old 05-08-2013, 05:20 AM
Master Builder
 
Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Structural Slab for new WFO

Got home early enough from jobsite. New house is near Honda automotive manufacturing- Kiyohara. There are alot of "just in time" suppliers located in the same area--so there is a real rush of traffic in the mornings and repeats around 5-7 every day. If I get to jobsite before 7AM then rush is avoided--if I try to start like normal people at 8AM (takes 2 hours) to travel to site vs 35 minutes. Dah! Start earlier...

Tonite was second burn--for curing (no rhyme or reason) but this time the insulation layer of dome was cool to the touch and so was all the render.. Sunday's burn must have driven a lot of the moisture out.. Castable refractory showed no signs of distress -- maybe a few more burns then "light it up for real"!

No new cracks on pericrete or render--must have been like you said --Davids--water has to get out, and steam builds pressure.. Relief valve are the cracks!

This week-end, have to see how high of a flame I can get roaring out of the chimney--see if stainless melts! Whoopie!

Lots of short; dry, pine scraps from jobsite too! --good to get an initial bed of coals then go for the good stuff--dry oak or ash!
Reply With Quote
  #165  
Old 05-09-2013, 07:04 AM
Master Builder
 
Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Structural Slab for new WFO

Tonight, repeated yesterdays' routine. Started with some kindling that started almost immediately when you put fire to it. Monster took off burning right away. Added a couple of pieces of oak and let it burn --most of wood was consumed in flames--but right before going to coals, pushed everything to center and rear. Whole flame pattern changed--instead of flames licking forward--now the tips pulled to the rear and washed the dome with their tips.
Even the coals began to glow more brightly. The oven was drafting real nice and only hot vapors were being emitted from the chimney!

Nice to see the oven burn so clean. Even the pericrete and render stayed cool..must be an indication that the moisture is beginning to be drawn out. have to do the same tomorrow. A nice chicken might cook now, but chicken in one piece is a rarity in these parts. You can buy dressed chicken breast (8 nice pieces- 2 KG- for $4.50/pkg) but if you can find a scrawney chicken in one piece--they want $12.00 for this bird! Rather buy a slab of pork loin for the same bucks--Have to figure out how to do one of these in a WFO--in slices deep fried....I know the routine.
Reply With Quote
  #166  
Old 05-09-2013, 01:00 PM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,787
Default Re: Structural Slab for new WFO

The seven fires in seven days routine is designed so that people do not jump to big fires straight away. You should proceed slowly or you are asking for more trouble. If you see visible steam then you are going at it too fast, back off. Flame up the flue is also a no no and asking for trouble.

Think of your oven as anew car. You wouldn't jump in it and drive it up to max speed the first time you drove it. Be a gentleman and treat it gently.

Last edited by david s; 05-09-2013 at 01:03 PM.
Reply With Quote
  #167  
Old 05-09-2013, 01:22 PM
Master Builder
 
Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Structural Slab for new WFO

Hello David s!
That was a joke about trying to see flames out of the chimney. But I have no doubt if you put enough wood in at one time, there would be flames jumping out of the top... right now, I have pipe scaffolding surrounding the oven and galvanized scaffolding planks on the top--I want to be able to put a tarp over everything in case we get rain-- cannot build any kind large fire.

There has been no visible steam anywhere, but when I uncover the WFO in the evenings after having it covered from when I leave for work--5:45 or so, there is moisture on the pericrete/and render. But nothing feels hot anytime on the exterior of the oven--at anytime anymore.

Gotta see if I can find a chicken somewhere to cook. Only whole chickens I have seen recently were the frozen variety from Brazil--they look more like Robins by their size. Only things that fly around here are crows and ravens, little too chewy for my taste if you could catch one--"no guns in Japan" except for the police, military, and underworld groups.

I don't know if cars need to be broken in anymore.. with old type bearings, that may have been the rule...I think the new engines could go 100% right off the line and do fine! But I don't know anything about things like that---my wife tells me I don't know anything about anything! She says that I keep on "jabbering only to hear my own voice"...maybe its true! Get senile from hearing foreign words all the time ---

As far as being a "gentleman", I am practicing singing country songs --my the late "George Jones" while driving to work. The Japanese drivers must think I'm nuts to be mouthing words behind closed windows...Or maybe they think I'm just another "stupid foreigner"! Probably both true! Cheers!
Reply With Quote
  #168  
Old 05-10-2013, 04:47 AM
Master Builder
 
Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Structural Slab for new WFO

Great news! found two dead frozen chicken from Brazil! I don't speak Portugese so I could not ask them if they were good or not! 1 KG - 500 yen! What a rip, could get breasts for same price but 2KG! Sure love breasts

The oven got a day off! Saturday will be the 4th gentle burn, and I hope the frozen chicken is thawed by 6PM. If you have a special recipe for frozen chicken (always welcome) for first WFO feast! Have a cast iron deep fry pan with pyrex type lid--works for regular ovens! So, if I am gentleman-like--it should be O.K. for the wood recycler!

Oven turns dried burning oak into fluffy gray ash! Back to nature!

Something addicting about a flame--just like watching it and enjoying the warmth!

What do other people do to get a whole chicken? Grow their own? Maybe another good idea--except they would get names right away and then it would be difficult to eat someone you knew on a first name basis!
Reply With Quote
  #169  
Old 05-10-2013, 07:17 AM
david s's Avatar
Il Pizzaiolo
 
Join Date: Mar 2007
Location: Townsville, Nth Queensland,Australia
Posts: 4,787
Default Re: Structural Slab for new WFO

[ Have a cast iron deep fry pan with pyrex type lid--works

What do other people do to get a whole chicken? Grow their own? Maybe another good idea--except they would get names right away and then it would be difficult to eat someone you knew on a first name basis![/QUOTE]

rule number one. Never give an animal you intend to eat, a name.

We always use the open roast technique. Ie without a lid. It crisps up the skin yet the meat is left delightfully moist.
Reply With Quote
  #170  
Old 05-10-2013, 07:26 AM
Master Builder
 
Join Date: Jan 2013
Location: Tochigi Prefecture, Japan
Posts: 620
Default Re: Structural Slab for new WFO

You never fail!
Thanks for the advice, tomorrow is "frozen brazillian chicken" no name, baked in a WFO with no lid!
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Started in Napa, WFO dome & slab questions EricU Getting Started 9 08-01-2010 12:08 PM
Foundation Slab Questions achilles007 Newbie Forum 5 07-06-2009 04:52 PM
structural slab question rbigante Pompeii Oven Construction 2 10-01-2008 07:44 PM
structural slab question rbigante Pompeii Oven Construction 5 09-29-2008 10:42 AM
New hearth slab design question DrakeRemoray Pompeii Oven Construction 6 04-24-2006 01:42 PM


All times are GMT -7. The time now is 03:20 PM.

Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
© 2006/10 Forno Bravo, LLC