[Cob] Floor Update and Cob Rocket Oven Project

[Dulane]

I have been working on 2 projects this summer. I am finishing my cob floor,
and rebuilding my old deteriorating cob oven. Photo links below.

 

1) I hired an experienced cob builder to pour a new 2” floor, using screened
materials. Rob Van Arsdale was great. He got it done in a day and a half
with the help of his right angle drill paddle mixer. I started, here in the
Seattle area, the first week of August. I wish I’d started in June! When the
2” floor dried enough to walk on, I did another ¾” layer of colored clay,
fine sand, 4-5 cups of wheat paste and 2 pounds of dried blood meal. After a
day of sitting in the sun, my floor color mix started frothing and developed
a life of its own! 

 

Unfortunately, August has been cool and damp for us, and I have been
sweeping light mold off the drying floor every other day for the last 2
weeks. Both wheat paste and blood meal have their own fetid odors, and it
has been impossible to sleep inside the hut since I started this, more than
a month ago. Finally I plugged in a fan, things look better and I’m tempted
to sleep down there tonight.

 

I really like the color, but it is drying lighter than I expected
terracotta
orange. I’d love to start adding the linseed oil layer(s), but I will wait
until it is completely dry. Then there will be more waiting and I’m hoping
that the linseed oil will dry in the fall months. I do have a wood heating
stove, but I have to cross the floor to keep the fire stoked. I hate to drag
a space heater down there.

 

I read on another internet cob floor report (from damp North Carolina), that
cob floors should maybe be avoided unless you can control your drying
conditions. Perhaps save cob floors for really dry climates. There is a dry
pouring method where you pour the floor almost dry and then use a pump
sprayer to dampen the surface and then tamp it and trowel or burnish the
surface finish.      

 

2) I am building a new cob rocket oven. I feel that ‘regular’ cob ovens with
the oven and fire box sharing the same area are so-so efficient. I wanted to
incorporate the rocket stove design, so I am building my firebox below my
oven (an area that is often wasted or used for wood storage in many cob oven
designs).

 

I was lucky enough to find some huge interlocking fire bricks sitting along
the road with a free sign! They are WAY overkill, but I am using them for my
lower firebox. They are so cool, they drystack with no air flow between
them. I haven’t seen pictures of them anywhere else, but they must have been
used in a boiler room or maybe actually designed for a mass heater?

 

I am building the fire box with them, then using a sheet of 1/8" steel for
the roof of the firebox (bottom of oven), then using a layer of standing
skinny fire brick for oven walls and using a 20 gallon stainless steel bowl
for my oven roof.

 

I am using red brick with holes in them for drafts, and I'm using tubing to
circulate heat around the oven and over the SS bowl roof...back to a chimney
behind the oven and above the firebox. My tubing will be toilet paper rolls
and carboard frozen juice containers, stiffened and formed with paper mache.
I've already fired my prototype, and there was minimal smoke
plus it went
just where I expected it to. I am designing it so that everything in the
front of my fire box area will be replaceable, because it is just stacked
bricks. That will make for easy cleaning too.

 

Eventually I'll cob over the whole top in some sculpted form. This project
will be a bit spendier than I’d like, but cheaper than buying a regular
oven. And we really do enjoy cooking outside. Most of the cost was building
the outdoor covering, and the steel parts. Other components were recycled.


 

I haven't worked out all the details yet, but I'm excited about it, and I
will photo the whole project. I need to say that I got the idea from Ray
Cirino's design that he shared with us last spring. When I found those fire
bricks I knew I was destined to do this.

 

Cob Floor

http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view
<http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view&curre
nt=doorfloorA.jpg> &current=doorfloorA.jpg 

 

Old Cob Oven with visitng garter snake seeking solar heat

http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view
<http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view&curre
nt=oldoven.jpg> &current=oldoven.jpg 

 

Rocket Oven Lower Firebox

http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view
<http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view&curre
nt=firebox.jpg> &current=firebox.jpg 

 

Oven which will sit on top of metal roof of firebox   

http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view
<http://s151.photobucket.com/albums/s143/Dulanec/Summer10/?action=view&curre
nt=ovenbowl.jpg> &current=ovenbowl.jpg