Cob 4 cob questions

[John Schinnerer]

Aloha,

> -----Original Message-----
> From:	JohnBoik at aol.com [SMTP:JohnBoik at aol.com]
> 
Well, most of the answers I'd give would be "it depends..." - more
specifically:

>1)  For a two-person work crew, what would be the optimal size of mixing 
>machine (in cubic yards) for one days worth of cob.

Kinda depends on the answer to 3)...sort of the same question asked another
way...the usual optimal mixer size for two people is four feet... ;-)

>2)  Using the tarp/pit method, how long does it take two people to make a 
>given amount of cob (for example, ? hours to make a batch of ? cubic yards
of 
>cob)?  

Kinda depends on how often and/or how far they have to go to obtain
materials, how slow or fast they dance, what their physical capacity for
cob-mixing is, whether or not they sing and/or drum while they're mixing,
whether or not the clay has to soak first, and so on...most cobbers I've met
tend to talk in terms of how many inches they've added to the walls rather
than how many cubic feet or yards(!) of cob they've mixed.  

> 3)  On an average six-hour work day, how many cubic yards of cob could a 
> two-person crew place on walls (excluding the time it takes to make the
> cob)?
> 
Kinda depends a lot on the climate conditions at the building site...can't
put it up faster than it sets up enough to allow more to be added.  So a dry
breezy sunny site might enable a whole lot more building per day than a
damp, calm cloudy site...and then there's air temperature...air movement
seems to be the most important factor, all else being equal...see also the
above about inches laid on the wall vs. cubic measures (which also depends
on the thickness of the wall...).

> 4)  On the average, how much straw is added to a mix (for example, ?
> pounds 
> per ? gallons of cob)?  
> 
Well, just the right amount to give it enough but not too much, which kinda
also depends a little bit on the nature of the rest of the mix and what it's
going to be used for (more long straw for corbeling cobs, strapping cobs,
etc. and less for plain 'ol cob to add to the wall; chopped straw for rough
plastering cob; etc. etc.).  It'll feel right underfoot when the straw
quotient gets about right, y'know?

In short, I've never worked with anyone who measured any of this stuff,
especially not in industrial units like cubic feet.  The closest I've seen
are localized rough ratios of how many buckets of soil/sand to a bucket of
clay, and localized estimates of how many inches the climate allows one to
put on a wall on a "typical" day (assuming there's enough folks working to
make and add that much).  You may well have to go and research this
personally to get the kind of data you're looking for - keeping in mind that
any data you get is fairly site-specific!  ;-)

John Schinnerer