The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Alan Scott ovens

wally's picture
wally

Alan Scott ovens

Does anyone have experience baking with an Alan Scott wood fired oven?  Starting this Fall I'll be baking using one and my experience so far is limited to baking in commercial gas ovens.


Any personal experience or book suggestions would be appreciated.  I'm less interested in construction details, and more in the process of using one and what major differences to expect from my experience with gas (I'm baking with a small 4-deck Italian oven presently).


Thanks!


Larry

swiggin's picture
swiggin

I have no real insight on Alan Scott ovens, other than saying I use one- built from his plans. There is a community WFO near where I live in Toronto, and I'm able to arrange the use of the ovens once a week, when there is residual heat. From my limited experience I can only share some of the obstacles that I have encountered. First, and lastly, the more times you load the oven the better the results will be (obvious, I know). For a number of reasons I have found it to be different: loading the oven can be tedious (small mouth to the oven), figuring how best to load the oven (what loaves go in first) and the timing/temp, how to adjust proofing and scoring (especially if unsure when the oven is at opt. temp.), and how to get the desired crust (through steaming/temp). The variables are similar to a home oven, but i find it's a matter of adjusting them. I find the results at home to better because I have found how to best control those variables in my oven, but love the experience of the WFO (and the results are getting better). Anyways, good luck with WFO, I am sure it will fun, as- "Baking bread in a brick oven awakens your past. It takes you back to who you are." -Poilane


Seth


P.S. No book suggestions other than The Bread Builders - Scott and Wing. Sorry I'm able to go more in depth of the process, but people with knowledge on the subject should be able to help.

wally's picture
wally

Seth!  That's all useful information you provided.

CarlSF's picture
CarlSF

If the Alan Scott oven does not have thermocouples, then I would suggest maybe using or obtaining an infared laser thermometer, so you can get a readout of how hot the hearth really is.  Different parts of the hearth might have different temperature levels.  When I took a wood fired oven course with Alan Scott, he said that the breads will generate their own steam, so there is no need to add additional water to create the steam effect that you might need.


Carl

wally's picture
wally

Thanks Carl!  We've got one and I intend to use it.  You comment on steam is very interesting since it's used commonly used in commercial ovens.  I'm guessing that the higher temps in wood-fired ovens might mitigate the need for steaming?

swiggin's picture
swiggin

Although I have heard/read the same thing as above-about the loaves creating enough steam, I think it really depends on how full your oven is, and perhaps how many times you fill it after a firing. What I tend to do is similar to what most do in their homes- heat a heavy pan then put water into it. I have also heard to spray a 'fine' mist with a nozzle from a hose- the water immediately turns to steam, so no need to worry about thermal shock. Here is an example (albeit a little different):  http://www.youtube.com/watch?v=u4RiJs1a92U


Seth

wally's picture
wally

Thanks again Seth!

ClimbHi's picture
ClimbHi

I have a small one, and use it every weekend. Look at my earlier posts in this folder -- lots of examples of Scott-style baking, and a link to my Flickr page where you can check out some pics.


As for books, "Cooking with Fire" and "Wood Fired Cooking", both available on Amazon. Also, Scott's own book "The  Bread Builders" has a lot of info on bread baking.


ClimbHi
Pittsburgh, PA

wally's picture
wally

Thanks - I'll check out your posts!

gregnim's picture
gregnim

I've been using an Alan Scott type oven for over a year now and the thing that I have the most trouble with is timing: will the oven and the loaves be ready at the same time. In my experience, there can be one to two hours difference in my oven coming to baking temp, from kindling through fire burn-out to letting the oven cool a bit. To make it even more interesting, I use exclusively sourdough, so that gives me a variable on the other side. But is is an experience thing, and I am getting better. With regards to steaming, when my oven is full (eight to ten loaves), there is no need for additional steam. When there are only a few loaves, I add hot water to the small cast iron fry pan filled with rocks I keep in the oven. Be very leery of spraying too much water in a hot brick oven; I've heard of too many instances of brick deterioration from excessive water.
I wish you well,
Greg

wally's picture
wally

Greg-  Thanks for sharing your experiences.  I suspect we'll be baking mainly pain de campagne and a variety of rye and wheat breads, and getting the timing down will be an interesting challenge.  Your observation about potential effects of excessive spraying I'll take seriously.


 

ClimbHi's picture
ClimbHi

Here's the secret to timing: consistency.


The heat output and heat profile (how fast the heat is released) of wood varies enormously depending on the species, the size of the stick, and the moisture content. I bake naturally-leavened breads almost exclusively, so timing is always a major consideration. I discovered early on that the best way to crack that nut is to develop a process that is repeatable. That's easy when you're using a gas or electric oven, but takes a bit more effort when your fuel is as variable as wood.


The easiest way to achieve consistency is to maintain strict control over the wood you burn. My favorite wood source is getting logs from local tree services. I cut, split and dry them myself, so the stick size and moisture content is consistent. I also end up with a whole wood pile of sticks from one, or maybe two, trees. I coke enough wood for the next fire at the end of each bake.


Sure, I toss in some scraps from the workshop just to use 'em up, and act as kindling, but the heat source for the bake is primarily a load of wood of a predetermined quantity of a single species of wood (maple is my favorite), dried and coked, of relatively consistent size. This allows me to time the firing to within 10 or 15 minutes every time, if necessary. (When I'm baking less time-sensitive goodies, I typically use other wood - maybe not as dry, bigger, etc. -- saving the "good stuff" for bread baking.)


ClimbHi
Pittsburgh, PA

wally's picture
wally

As with everything else in baking!  Thanks for passing this along - you're providing me with exactly the type of info I need to bring my learning curve a little lower.  I suspect we can find suppliers of wood for wood stoves that would fit the bill in terms of size, age and type of hardwood.


Larry

CarlSF's picture
CarlSF

After reading what Seth and Greg said, it sounds right that filling up the oven with loaves of bread dough should generate enough steam.  As for higher temperatures, I am not sure about that.  I've never used an Alan Scott oven...just built one with Alan.  I have heard reports from other people who have used Scott's oven or brick ovens that they had problems trying to get the temperature of their oven just right in order to match the timing of the fermentation of the bread (when it's ready to go into the oven).  I think this is what Greg was saying.  However, I think after using the oven several times and keeping good notes, you can probaby nail the oven's target temperature and the readiness of your loaves.  If you're going to be using this oven, maybe you can asked the person who has used it before in order to get a sense of when they fired up the oven and when they loaded their breads into the oven?  That might give you a good frame of reference to go by.


If you're going to bake a whole batch of loaves where you will be filling up  the oven, and then unloading your breads and filling up the oven again, I remember Scott mentioning that the oven should rest for 15 to 20 mins with the door closed in between refills.  This will allow the oven to heat up a bit.  After that, you can load up the oven with more loaves.


Carl

wally's picture
wally

Carl!  I was wondering if successive bakings are done one right after the other, or whether a break allows the heat to even out after having loaded and unloaded loaves.

CanuckJim's picture
CanuckJim

Larry,


I built an AS design 4'x3' oven almost ten years ago now.  I've baked in it commercially for almost as long.  For the past six years, I've been holding two-day wood fired bread baking workshops at my facility to the north and east of Toronto.  People have come here from all over North America, New Zealand, England and Holland to attend and learn the techniques involved.  After repeated requests to do so, I put together an e-book that covers what we do here.  It's not a recipe book as such, it's a book of wood-fired baking methods centered around seven very different breads.  All of the concerns you have are covered in depth.  You might want to check out my website, www.marygbread (Carswell House Books page), to find out more.


CanuckJim

wally's picture
wally

Can you resend me the link - the one in your message isn't working.  I'd love to check out your website and ebook!

Roo's picture
Roo

add .com to the end of the website. www.marygbread.com.  My wife and I are heading up to go through Jim's class the weekend of April 17th.  We are really looking forward to it!

wally's picture
wally

Yes, that would help, wouldn't it.  Thanks Roo!

CanuckJim's picture
CanuckJim

Wally,


Whoops, try this: www.marygbread.com . That should work.


CJ

BakerBen's picture
BakerBen

Hello, never used a forum so excuse me if I don't know all the protocol.


I am seriously planning to build a brick oven and am leaning toward an AS.  I went to the Asheville Artisan Bread Festival and attended a wood fired oven workshop - had been read books and online but that workshop pretty much sinched the deal - talked to a Greek mason tonight and got the first estimate. This guy has built more than 50 brick oven - most of them are round - he says woodfired ovens are extremely popular in Greece. 


I have a couple of questions.  First, I would think I should purchase the Alan Scott plans - obviousely.  The question I have is should I get Plan package #01 or #02.  There must be a difference in the thermal mass between the two sets of plans - website description is pretty brief.  I would appreciate any feedback on this question and also thoughts on the size - I don't know if 36 by 48 would be too big for my needs but I keep seeing comments from folks talking about wishing they had a bigger oven. 


Thanks,


Ben

ClimbHi's picture
ClimbHi

I built an AS oven -- you can get a link to pics etc. by checking out my earlier posts in this folder.


I got the plans (#1) because mine is attached to my house which meant I needed to pass inspection and follow codes, etc. Having the published plans made my inspector happy and avoided my having to get my own plans stamped by an engineer. I used the smaller plan set and made my oven a bit smaller than I would have liked -- about 24" deep by 36" wide inside -- due to space limitations. But in my experience, 36" X 48" (the biggest of the three included in the plan set) is more than you would likely need for family use.


On one hand, I sometimes wish I had more room. But on the other hand, I've never had to forego anything for lack of room, and I appreciate that my oven takes less wood (and time) to heat to baking temps than a bigger one would. And since my uses are modest, I'm happy to be on the small end of the scale. If you want a more robust heat curve, you can always add more mass to even a small oven by increasing the thickness of the walls.


Every WFO is a compromise. You need to figure out what your typical use is and design for that. If you only plan to bake 20 pizzas once every year, it would be a mistake to design the oven for that use, since the firing requirements of that large an oven would discourage you from using it on a regular basis for the rest of the time. Design you oven so you can get the most frequent use out of it. Which, for home use, generally means a bit smaller than what you might presently imagine.


FWIW, I wouldn't rely on the AS plans alone. I'd suggest you get his "Bread Builders" book as well. The book gives almost enough information so you don't even really need the plans, and provides information not included in the plans. (If I recall, I only got one piece of info from the plans that wasn't in the book -- something about the recommended ratio of one of the mortar mixes or something.) Also, a few of us in this forum have suggested a couple of minor changes to the design that you might want to consider. Again, a search through the older posts in this folder would be time well spent for you if you do this project.


If you do decide to do this, feel free to post your questions and ideas here. We're delighted to help out fellow WFO-ers whenever and however we can. Oh, and if you're even modestly capable with your hands and some simple tools, don't be afraid to tackle this as a DIY project.


ClimbHi
Pittsburgh, PA


PS: You might want to consider starting a new thread for your questions so they don't get lost in this old thread.

BakerBen's picture
BakerBen

Thanks for your reply - I have read the posts that referred to a SS ash pan and chimney shelf - are there others?


I have been pursuing baking via culinary school and working - Great Harvest, La Farm Bakery (Lionel Vatinet) and Zingerman's Bakehouse in Ann Arbor (just a couple of weeks while on vacation).  My original hope was to build an oven, learn to use it and then bake a modest amount of bread to sell.  I have checked on my zoning and unless the oven is inside my house I can not use it to bake bread commercially as a home baker.  That news was disappointing but I still plan to build it - I may give some loaves away anyway :-). 


I would like to do this project myself but my wife is a bit reluctent - she is very supportive usually but I believe she has her doubts as to (1) how long it would take me and (2) what the final result may look like.  I am legally blind and even I know there are some tasks which may be better left to a professional based on my visual limitations - also I am sure I will be baking in the oven this summer if I go the mason route. 


Based on my forum reading you seem to be a very knowledable WFO guy and DIY too - is this just a hobby with you or is it your career?  Also, what is the policy for starting a new thread (i.e. when do you do it).  I obviousely figured that thoughts concerning AS ovens went here - newbie error.  Again, thanks for your reply.


Ben

ClimbHi's picture
ClimbHi

There are a few other suggested modifications by another poster -- I recall he recommended hi-performance insulation and a cast refractory lintel. That said, the oven as designed by Scott will work fine.


There's no "Policy" on starting new threads. Just click on the "Post New Forum Topic" button in the header, make sure you're in the right folder, and post away!


This stuff is not my career -- doesn't pay enough! ;-)


It's not that hard to build your own. My wife (aka My Lovely Assistant) is the the type who can't sit around and watch somebody else do something -- SHE wants to do it. She did much of the work on our WFO with only some supervision from me. This is not a particularly advanced masonry project -- it ain't holding a house up! It may take you a bit longer, but if you have an itch to DIY, don't be scared off. Read up, maybe find somebody who has some experience who can give you pointers and maybe a "lesson" and have at it.


Just a word of caution -- if you go the mason route, be aware that many masons will try to talk you into changing the plan based on their knowledge and experience with fireplaces. DON'T DO IT! A WFO is NOT a fireplace. Have him follow the plans.


Here's some Flickr pics of the building process we went through if you didn't pick up the link from one of my earlier posts.
http://www.flickr.com/photos/climbhipa/sets/72157613634415857/detail/
You'll note that our WFO isn't really inside our house -- just part of the back porch. If you can do something similar, ie, attached, you may be able to satisfy your local code.

BakerBen's picture
BakerBen

Hi ClimbHi,


Thanks for the reply and encouragement.  Your photos are really nice and your oven too.  One thing I have really appreciated after looking at a lot of WFO online is the creativity of the builder that DIY - some are truly works of art.  I am sure you get a lot more satisfaction when you can tell someone who is totally enjoying your bread that you, and in your case your wife, built the entire oven yourselves - what an achievement. 


Well, I am going to get off this OLD thread and when I speak again it will be to reply on a currently ongoing thread OR one that I start.  This is a great way to share information with like minded - at least on the topic of bread - people who are as enthusiastic as you are.


Again, thanks,


Ben

CanuckJim's picture
CanuckJim

Ben,


I'm the other poster referred to by ClimbHi.  You can check out my AS oven at www.marygbread.com.


One weak spot in the design is the use of angle iron to span the top of the oven mouth.  Iron and brick expand and contract at different rates, which can and probably will lead to cracking over time.  I'd suggest instead building a simple form of the same size and casting a lintel out of the high strength refractory: Kastite.  Basically, you'll be making a super strong giant firebrick.  Let it cure for at least a week before removing the form.


Using four inches of high heat insulation board like SuperIsol (one brand name among many; very dense can bear weight) or K-Fac 19 (one brand name among many, less good at bearing weight) will be much more efficient than any Portland/vermiculite/perlite mix. Three inches of high heat ceramic blanket like Durablanket (one brand name among many) is more efficient than six inches of loose vermiculite and is soft enough to conform to the curve of the dome. Once done, make a cage of galvanized chicken wire over the blanket and trowel on three to six inches of the castable refractory insulator Matrilite 18.  Believe me, this really, really works.


Supply of these materials can be an issue, depending on your location.  Have a look at Chicago Fire Brick on the web to find a dealer near you.  Alternately, contact the local potters' group; they've been using this stuff for years.  By the way, all are silicates, so be sure to wear a mask.


CJ   

Roo's picture
Roo

Jim can you clarify the hearth slab construction?  Are you only using the 4 inch SuperIsol and then placing the fire bricks on top of that to creat the oven floor?  Is their any refratory or other cement cement used for the hearth slab?


Tom

CanuckJim's picture
CanuckJim

Tom,


That depends on what you're building.  An AS oven uses a suspended refractory slab below the hearth bricks as a heat sink.  Scott specified a six inch Portland/vermiculite mix below the slab as an insulator.  Using four inches of high heat board (the softer and cheaper K-Fac 19 would work just fine) instead would be much more efficient, but only after the slab has cured and is very dry.  Scott has a formula for a fireclay and sand mix to bed the hearth bricks on the slab.  That works just fine.


Round Italian pizza ovens, such as the Pompeii style, are commonly built with the hearth brick bedded on two to four inches of high heat board.  These ovens heat fast but don't retain heat as long as an AS oven.


Fine fireclay can often be gotten from pottery kiln suppliers.


 

BakerBen's picture
BakerBen

CJ,


Thanks for the information - by the time I need it I will hopefully understand it all a bit more but in the mean time I will definely keep the information noted. 


I looked at your website at Mary G's - a beatiful oven but even nicer bread.  You are truly and artisan of artisans at both brick and flour - tour breads are really really nice.  It sounds like you have evolved professionally over the years with the necessay experiences to become a great baker and produce bread that is not only beartiful to look at but I am sure wonderful in taste too. 


I had a really close friend, Susan, who grew up in Parry Sound abot 200K north of you.  I know the summers are pretty but the winters can be extremely cold.  Do you do all your baking for yous bakery in your WFO?  Do you have a bakery store front or do you sell in some other manner?  How big is your bakery - peoppe and number of loaves per week?  I am not being so noisy as wanting to get a feel for you operation.  My goal is to learn enough to hopefully in 2 to 3 or 4 years open my own bakery.  I have been at the task of getting experience for about a year and a half now and love it.


Thanks again for the great info.


Ben

CanuckJim's picture
CanuckJim

Ben,


Thanks for the kind words.  I've been at it quite a while.  My area (50 miles north and east of Toronto in farm country) simply does not have the demographics to support a high end wood fired artisan bakery.  If I was in downtown Toronto, things would be very different if I had half a mil $ to start up.  Anyway, tried retail for a while and got pretty beat up doing it.  Now I do large restaurant orders and catering.  Generally, my partner, Wendy, and I do all the baking, but I sometimes call in more people for really large orders.


However, I'm so busy giving workshops on weekends and installing WFOs during the week in good weather, that commercial baking has been pushed somewhat to the side.  The web is a curious experience: Among others this past weekend, I had Tom (a member here) and Charlynn from near Omaha, Nebraska, at a workshop.  Week before that it was Mary and Cookie from Beaumont, Texas.  Even had Ros from New Zealand a few years back.  Great way to meet the world in rural Ontario.


I've found it's impossible to duplicate the loaf volume, crumb and crust from a wood fired oven in a commercial gas deck, although I do make pan breads and such in an appliance with dials.  This area is the banana belt compared to Parry Sound in winter; all the snow ends up in Rochester, NY, south across Lake Ontario.  The oven really isn't that affected by cold weather, but I am.  February is out, therefore.


Every year, on the Saturday of the last weekend in May (the 29th this year), we hold our annual Bread & Pizza Bash.  It's a party, really, $10 per person to cover ingredients.  I demo a few pizzas, pitas and such, then turn the ravenous crowd loose on a 750 degree hearth.  We sure get some unusual looking pizzas (think the shape of Africa), but everyone has a great time.  Anyone on this forum is welcome to attend.  Wood fired types from all over the place, even my refractory supplier, show up.  It's a BYOB event.


Shoot me an email and let me know how many people are coming, and I'll return with location and accommodation info.  Taking a bit of time to explore Toronto afterwards would be worthwhile.  Stay out of the cheese shops or leave your credit card home.


CJ

idiotbaker's picture
idiotbaker

Dude, that looks great!  I want one.

jmos's picture
jmos
CanuckJim's picture
CanuckJim

Alan Scott died in February on a trip back to his native OZ.  I had the pleasure of meeting him several times, and his self-description as an "aging hippie" was quite accurate.  He was a bit stuck in the past and darned proud of it.  Even so, he was a pioneer plus guru, and his death has put a large and gaping hole in the wood fired oven landscape, which he did most to describe and populate.  His work is carried on by his daughter and son at www.ovencrafters.net.


CJ

farina22's picture
farina22

I see that you're an East Coast guy. Jim Wills at Mary G's teaches classes at his place in Canada and is extremely knowledgeable about Alan Scott ovens and breads. You can find him here on the site somewhere.


I teach wood-fired oven classes in Sonoma County, California. There are many differences, I find, between wood and gas ovens, but the learning process is the most fun there is IMHO.


Best of luck!

CaperAsh's picture
CaperAsh

I just stumbled on this thread (after building an oven I noticed the brick oven section on this fantastic forum!) and ordered the book mentioned above - Tools, Hands etc.

Looking forward to it.

First batch about to come out now. Oven did not get hot enough because still residual moisture I think, or I have to fire it longer. So this batch is a dud being cooked at around 325 or so and I over-fermented the dough by leaving it out last night by mistake so it was very, very wet and mushy but I didn't want to use baking pans for my first load.

But since the dough is made with good organic ingredients and some very flavorful wild starters, I know it will taste just fine even though it won't have beautiful crusts nor a decent rise.

10 more minutes or so and out it comes!

thamnophis's picture
thamnophis

Has it been mentioned that generally the design in Scott's book is now considered flawed? The insulating slab needs to be placed above the structural concrete slab - which also simplifies things in the building - no need to create that hanging re-bar slab.


The idea, as I understand it (and I'm no expert), is that you don't want a big heat-sink under the fire brick. The insulating slab (vermicrete or perlcrete) should function to keep the heat in your firebrick.


 

CaperAsh's picture
CaperAsh

Am no expert either, but I went with the non-AS variation by putting a slab on top of the cinder block walls, then a layer of K-Fac 19, then 2 layers of firebrick as the heat sink and so on. I just didn't like the idea of suspending the slab, which was part of the heat sink, on the cinder blocks and with vermicrete underneath, preferring to have the heat insulated above the slab, which at this point is simply structural support for the oven on top. That said, many people have built AS ovens, used them for years commercially (as well as domestically) and they seem to work fine, also if properly made the underneath vermicrete prevents too much heat leakage into the cinder block walls. His design makes it easier to move and replace the oven if you ever want to do it.


 


If I was doing it again, and since this is in internal oven, I would make an all steel base, on top KFac (or whatever), then the oven on top.


When using K-Fac (or whatever) best to have something (could be just aluminum foil, or concrete board) to protect it from friction and moisture. It degrades rapidly with any moisture.


I never laid a brick in my life but find with 3-4 hours of firing, plus 2 to come down, that I can bake 4 batches of 20-25 loaves in my 36 * 49.5 oven, albeit the last batch is barely at the 400F level, and this assumes I start baking the first batch at around 650.


I did find the transition around the front, the door and chimney area, rather challenging and because I had miscalculated the size of the base relative to the internal size of the oven (lengthwise, not widthwise) had to cut corners and break various rules, but it seems to have worked out just fine. For example, I dropped the front wall straight down over the lintel and also made square corners at the end into the doorway. Then I have only 12" from the front of the hearth and that lintel to the outer lintel. So the air has to drop straight down in the oven chamber to get out through the hearth lintel. On the excellent Brick Oven Yahoo Groups forum, this general approach is not recommended (no doubt rightly), but the oven burns very well, I get almost no smoke in the bakery during firing and raking out etc., it draws just fine and I have not noticed that having all these square ended transitions obstructs the air flow. And doing it 'my' way made it very easy. Both the hearth and front lintels are from 3" angle iron pieces, not more brick arches, so that is really very easy to do.


I also used a steel harness around the length and width of the oven to contain the vault. Because I have a neighbour with welding skills this was not all that hard to do. But otherwise making the outer layer of concrete with rebar re-inforcement etc. is a must. I don't have any. Just the harness, then insulation then a thin layer of stucco around the insulation (mainly mineral wool which is quite cheap and very efficient, but also one layer of ceramic blanket).


My only big worry is that since I built this 10,000 pound behemoth inside an old 1970's vintage trailer (which some welded steel supports to the trailer frame underneath), it is pushing the trailer into the ground underneath the oven and I am having a hard time lifting it back up to level, meaning there is a risk the whole thing will get out of wack and the oven will crack. That was poor planning at the beginning. Hopefully it will all work out though and I'll find a way to brace it properly from underneath next spring and it won't collapse this winter! Again, according to all guidelines, this is not a good idea (putting inside a trailer etc.) but it seems to have worked. Hard work, but great fun.


The timing is indeed a big issue, both in terms of synchronizing dough and bake-start time, but also in loading the oven. It takes a while to get loaves on the peels, position them well in the oven, meaning one row is in there well before the last row, and therefore they have to be removed in proper sequence as well.


It is also true that if you wait a while between batches (which I rarely do because I simply keep forgetting!) that the oven will heat up again as heat is exchanged between the hotter outer levels and the slightly cooled-down inner levels (cooled down by the baking and also having the door opened during unloading).


Very satisfying when you get it right.


Here is a pic of recently made 100% wholewheat baked at 650F for 30 mins, 800g loaves ,70% hydration (loaves are darker than the flash pics make them seem, also oven is much cleaner-looking since flash heightens contrast etc.):


Loaf and crumb 100% Whole Wheat


 


I got the Mary G Bread book after reading through this thread and found it quite enjoyable, although not nearly as much about the various logistics of managing a wood-fired oven as I was hoping for, especially in terms of timing issues. Two tips I came away with though, that have 'stuck'.


1. Water is a baker's friend. I use it now for shaping (versus adding flour), also increasing the hydration in the recipes when cooking in higher temps


2. Baking at higher temperatures works fine. Yes, you make pizzas at 700d and it takes only 2 minutes per pizza (or less) but also you can bake fairly large loaves at these temps and instead of 40 they take 20 minutes and are not burned to a crisp either. I find 650 better than 700 to avoid too much burning. The loaves in the pics went in at 650+ and were not burned at all.


When you get it right (and you don't always especially when learning), there is something extremely satisfying about using a WFO.

thamnophis's picture
thamnophis

From what I can tell - and I'm guessing to an extent here - once the corporate home WFO designers got into the picture some of the assumptions about design changed.


They emphasize a simpler model that amounts to a layer of heatsink material (firebrick in a DIY oven) wrapped with the best insulation you can afford.


If the heatsink is too thick the oven takes forever to heat up. 4 inches of masonry like firebrick seems to be what people aim for.


If the insulation is substandard then it may never heat up, or may loose heat too fast. The refractory blankets (ceramic and non-ceramic) are expensive but much more efficient that vermiculite or perlite. The recommended 3 inch layer of 8# density would save much on wood and labor it seems. 


It also looks like iron and concrete have essentially the same expansion coefficients (but look it up, I might be interpreting the data wrong!)


The once popular tinfoil layer seems to serve no actual purpose.


My remaining questions concern interior design. Do squared off ovens (much easier to build) *really* heat/cook poorly? Do low ceilings in a vault *really* cook better?


Much of what initially appears to "make sense" actually doesn't when examined. Keeping in mind that the whole purpose is to build and hold heat, and keeping it simple, helps.


 

CanuckJim's picture
CanuckJim

There are several questions and comments here that deserve answers/clarification.  First off, the idea that the Scott design is "generally" regarded as flawed just ain't so.  I've been in this business for over ten years, and I'd like to know who these generals might be.  In the last while, WFO building-supplying has become a very competitive arena, with lots of new kids on the block, each one with an agenda and a crying need to be "expert."  Some of the claims made about the superiority of one design (barrel vault/Neapolitan) over another, one method over another, one material over another, are simply balderdash.  Properly built, both will work just fine.  Thing is a round low dome design is more efficient for pizza, while a barrel vault is more efficient for bread.  That does not mean you can't bake pizza in a bread oven or bread in a pizza oven.  I've used both and built both.  The key word is "efficiency," not the design per se.


The idea that steam will cause brick deterioration is another red herring.  If that were true, why are there so many truly ancient WFOs in France that have steam injection systems?  I've been steaming my oven for a decade, and there's no deterioration whatsoever.  It is true that a full oven won't need much steam.  Anything less, though, and steam is required to keep the crust moist for the first half of the bake.  Otherwise, you will not get maximum volume in your loaves.  Try it both ways and compare results.  The term "thermal shock" should be retired from the lexicon.


As for the dreaded suspended slab, Alan designed it this way for a "high mass" oven, one capable of repeated bakes over time, one that would not bleed heat into the block oven stand.  It works, period.  The thicker the mass, the longer the heat up times, but the longer the retained heat is available (days in my case).  Want quicker heat up times, use less mass.  It's a matter of intent during the build stage, rather than anything wrong with the design. A single firebrick, even stood on edge simply does not provide enough mass for prolonged heat retention, no matter how well insulated.  Proper insulation, however, does provide more fuel efficiency.


The real point is that there is a lot of voodoo out there, whether about wild yeast starters or oven designs.  There are too many people seeking attention and wanting the well deserved mantle Scott wore.  Sure, there are ways to improve on his design: lintel material, insulation types, etc., but these are tweaks, not wholesale replacement.  Scott was well aware that WFO design is centuries old.  Beware those who will cheerfully tell you they've reinvented the wheel,


When I came to write my WFO book, now available as a paperback on Amazon.com and Amazon.ca, I considered using the logistical rules I've developed for my own oven.  However, I came to the conclusion after due consideration that such rules--the ones that work here--might prove to be misleading.  Reading through this thread proves the point.  There are so many different variables in build decisions (some of them just corner cutting), mass and insulation materials that hard and fast logistics simply will not work, oven to oven.  It has been my experience that each and every oven has its own personality, and logistical methods come from general guidelines applied to practical, hands on work with a particular oven.


CanuckJim

thamnophis's picture
thamnophis

Canuk Jim,


I aggree with much of what you've said. But just as there are new people trying to make a name for themselves, there are those who adhere to old ideas for their own sake.


I'm trying to find the truth, but there are many variables. Most importantly is the intention people have for their oven, as you mentioned.


I wish we could use thermo-simulation software to actually see the effects of some of the variables that have been discussed so often. The suspended slab, for instance, is a weak link in the sturdiness of the oven design - rebar rusts, after all.


And the time it takes to heat up a massive slab of concrete may or may not be worth many people's time. 


The dropped front of the Scott oven is complicated to build - what do we really know about how it effects baking? We can speculate, but as I said, much of the past speculation about design (to say nothing of actually baking) has proven to be unfounded.


Does heat radiate from the surface of the bricks at a 90 degree angle? If not, are slanted wall providing us anything? Since heat rises, is it really better to have a low ceiling? Maybe a high ceiling will help even out the heat? 


Like you suggested, there is a lot of voodoo in our assumptions - including past designs and we should also be circumspect about new claims too.


 

CanuckJim's picture
CanuckJim

Couple of things here.  Five-eighths rebar would take something like fifty years to rust through exposed to an extreme environment.  In the oven it is surrounded and protected.  Therefore, it's not a weak link in any sense of the word, unless we're after the longevity of the Pyramids.  If so, lintel iron over oven doors would rust much faster, and it's nowhere near as thick.  The major reason rebar gets into trouble on road beds is salt use in winter.


"Their own sake?"  These designs, barrel vault and round Tuscan or Neapolitan, have been around for centuries.  They've been measured and calculated over and over by oven builders, by bakers, who used the ratios for their own ovens. The astonishing thing about them over time is that the ratios and dome heights are consistent.  Are we that much more clever in 2010?  Don't think so in the face of such a library of historical information.  Have materials improved?  Certainly.  And we should take full advantage of them.  But if a proven design ain't broke, why does the drive to "fix" or "improve" it gain traction? There is no answer for that.  The designs work, period.  The ovens at the Bakery of Modesto in Pompeii were built before 79 AD.  Given their sophistication, there's no doubt the design was around long before that: low dome, small door, vent in the front, isolated from the bake chamber. Given the longevity and success of these designs, the word voodoo simply does not apply here. These are matematical formulae, not unfounded speculation.  If gas decks were an improvement, why aren't the products that come out of them better than a WFO?


It's certainly true that a high mass oven is not for everyone, so make it thinner. Though it does not, as is so often said without foundation, take "forever" to heat; overnight works just fine.  If you want speed, go for an Italian modular with a 2 1/2" thick floor laid on K-Fac.  It will not hold heat very well though.  The point is that Scott isolated the slab from the stand material by using the hanging approach in order to prevent heat bleed between the slab and stand.  It can also be done, not quite as efficiently or easily, using K-Fac between the slab and the stand. In either case, it should be done. Matrilite 18, a castable refractory, is a far, far better under-slab insulator than perlite/Portland will ever be.  R-value: more math.


Scott was not very good at all in describing the dropped front between the dome and the door, either in words or pictures.  I address that in Chapter 6 of my book.  Still, I've been recommending for years that the transition piece be cast in a gentle curve to improve combustion.  Kastite works just fine for this.  True, you have to build an accurate form, but it's no more difficult than laying brick.


Building a higher dome would absolutely destroy the ratio between dome height and door size.  Such an oven would draw like a turtle and smoke out the front. Believe me, I've fixed a few of these, sometimes successfully, sometimes not. Whether for bread or pizza, a lower dome contributes greatly to crust development because of the radiant heat from it.  So no, it would not "help the heat."  This is experience talking, not speculation or theory.  These ovens are designed the way they are for fast, efficient, bright fuel consumption through the venturi effect they create.  Change it at your peril.


In Spain and Portugal, there are higher dome ovens with the flue inside the chamber and hooks imbedded in the dome ceiling.  These are intended primarily for smoking fish, sausage and meats at cooler temperatures.  Purpose designed once more.


The whole idea in firing these ovens is to create a bright, absolutely roaring fire that gets to the secondary burn stage.  All the refractory materials in the chamber touch each other, and the intent is to heat all of them, top to bottom, side to side as evenly as possible, right through the entire thickness.  It's flame that heats the dome, hence low dome.


The "new" designs I've seen, and the unfounded changes to the old designs, are speculative to a degree in my experience, not founded on results or repeatability.  They seem based on nothing other than the drive to change them.  It's what comes out of the oven that counts.  The older designs have been developed over millennia, and the collective intelligence they contain should be both valued and emulated using contemporary materials.  Anything else is indeed voodoo.


CJ 


 

CaperAsh's picture
CaperAsh

Well, I cannot prove this but in my squared-off oven the back loaves seem to be fine but the ones in front on either side are often not so good, but also not so good rght by the door in the middle either. This is because I do not like to have the fire blazing right up to the door (and even so my metal-coated wood doors have been burning up, last time the baking-pan metal cover even melted). So my impression is that having it squared off is really not an issue.


One issue not addressed in most designs, which all emphasize insulation, insulation, insulation (and rightly so) is the loss through the mass going out the doorway and up into the chimney bricks. Some recommend a gap between the hearth bricks and the front area bricks which can be filled with simple vermiculite or KFac 19 etc. This prevent the heat leaching out into the bricks in front. I also had the idea (but did not follow through) of using kiln insulation firebricks as the first level in the chimney, also to break the connection between the inner vault bricks and the chimney bricks. Another solution is design things such that all bricks in front also are covered with insulation, but then you have to make sure that your door is not so long that you can't work the oven easily.


BTW, I do find that the expansion/contraction does crack the stucco layers in front and I think it is because of the difference between the steel harness metal and the brick, so am not convinced they are the same. But then it could be something else causing this cracking. When the oven is hot the cracks appear, then as it cools they disappear. In any case, the stucco layer is just to protect the mineral wool from dust, ash etc. which is insulating the heat with or without this outer skin layer. The bricks inside seem fine, as does the chimney; certainly no leaks or anything in any case. So I for one, for those with less experience with bricks etc., would recommend the square approach. Easy to make and plan, and works very well.


I also had my inner walls three bricks high (sideways, i.e. 2.5" * 3 = 7.5") and then made the vaults with a slightly more generous circle than the flattened ones (which start usually at 9" high). The result is 16" high in the middle, the same as the flattened approach. The benefit of the latter is tha there is less mortar between the bricks and the mortar tends to break down more over time. Of course the best approach here is to use shaped bricks which are available, although usually only in high density (HD) configuration, and the medium density is recommended more for baking (absorbs and gives out more moisture supposedly). So shaped MD bricks are best for the vault if you can find them, or so I suspect.


With anything I post here, I am not claiming to be an expert at all. Only recently built my first oven and am still learning how to use it.

thamnophis's picture
thamnophis

This is an interesting idea. Do you know of anyone who has tried it, or even of any discussions concerning this idea?


At first glance it sounds like it might be of help, plus it might simplify the difficult transition between the dome and the entry way.


 

MNBäcker's picture
MNBäcker

The class I attended this spring taught exactly that method. Instructor Derek Lucchese uses the glass wool as a "flexible joint" between the dome and chimney. Since the bricks in the dome heat up at a different rate than the chimney bricks, there's stress on that joint. The glass wool acts as a buffer of sorts.

Here's a picture of it:

I'm getting ready to build mine in the next couple of weeks and will employ that transition method.

 

Stephan

CaperAsh's picture
CaperAsh

someone on the Yahoo Brick Oven user group/forum mentioned this. I think he also mentioned doing it around the sides as well to isolate the heating slab from the support blocks.


I did a compromise: I put a slab on top of the blocks, then K-Fac19 on top of the slab except around the outside 5", but then a double layer of bricks on top of the KFac. The outer 5" was covered in the same insulation that came down from around the vault so in theory the slab is never exposed to any direct heat and doesn't act as part of the heating mass nor a medium for heat leaching out except what makes it through the K-Fac. It seems to work: at no time has the underneath of the slab got above 105F even when the oven has been fired very high with prolonged hard wood burn. Most of the time it stays within 5F of room temp. Also, the hearth and vault seem to keep roughly the same temperatures over time even though to begin with the hearth is hotter (from the coaling phase), then the vault is hotter (as hearth cools down faster esp. with bread going on it), but then after baking they all settle down to the same temperature and cool at the same speed - or so it seems from reading the surface temperatures (don't have internal probes).


The approach of making 2 slabs sandwiched with KFac 19 in between clearly works, but also is more work and slightly more weight. I really didn't like hand-mixing slabs so used bricks instead. About $75.00 more expensive, but MUCH easier to do!


AS's suspended design with vermicrete at the bottom has been used by many for years and seems to work fine even though it feels counter-intuitive to suspend everything on a few inches of re-bar sticking out all around. I watched a commercial baker using a 4' * 3' AS oven, which has been in continuous use for 10 years. It holds heat for hours and after ten years he has not had to replace any bricks inside. Clearly it's a solid design.


 

CanuckJim's picture
CanuckJim

CA,


This approach is exactly what I was getting at earlier.  Going in this direction for the hearth and insulation does not give you quite the hearth mass you could achieve otherwise, but it will work just fine.  I used the bricks on edge with a six inch suspended slab underdeath them, then a Matrilite 18 insulation layer under it all.  The total thickness is just about ten inches, but that was what I was after when I built the oven.  What you've done won't capture quite as much heat or retain it for as long, but it sounds like you got what you wanted.  Well done.


CJ