[Cob] Re: was tree-sculpted...now tractor cob

[Barbara Roemer and Glenn Miller]

Though I'm new to the list, I'm not new to cob.  Our addition floor is
troweled earth, our plasters earth over sheetrock, and we built a
Denzer-style bread oven and bench.  I've also worked at several other cob
sites and want to offer some input on tractor cob.  It is an excellent
alternative to foot cob for many people, especially in rural areas where a
friend or neighbor can often help out either for an exchange or for an
hourly fee, and many are eager to learn, as well.  (We live in the Sierra
foothills of northern California, 40 minutes from town, and know several
people with tractors.)  On bare dirt, at least in the summer, it's pretty
easy to see and feel with the tractor when you're down to the soil level
rather than in your mix.  It follows that careful measuring/mixing will
provide you with the proper proportions, and if you've made samples, you can
carefully control the proportions. Spending plenty of time mixing will
assure integrity of the mix.  Tractor cob can be mixed drier than foot cob,
cutting way down on splooging, and an important consideration when time for
drying is limited. By using form boards with tractor cob, the workload is
cut immeasurably, no small feat especially when cob takes so long to dry
out.   Using form boards and a tractor, a couple of people can put up a cob
wall in a day.  Even accounting for rental of a tractor, the vast labor
savings could be economical because you are freeing time for the roof,
windows, and myriad finishing details.  I am not advocating machine use
where it's appropriate to use handpower, but it's helpful to think about
total time expenditure on parts of your building.  My son recently built a
light clay straw mixer, and a big work party did 95% of the infill walls on
a 1500 sq ft. building in one day.  Now there is some interest from large
builders with commercial projects - perfect application for technology to
bear on natural materials.  Lots of ripples in the green pond.