[Cob] my 2 cents on the cob bathtub: 100 gallon mini-tsunami

[ocean]

Wrong, the 600-700 years of cob building experience has only proven 
that cob walls are excellent at resisting blown rain, with a good coat 
of lime.  Standing water on flat surfaces or pooled in a tub is a very 
different thing.  I don't recall seeing 600 year old cob bathtubs 
anywhere in the literature or vernacular :-)  So here we are on our 
computer e-list speculating about a cob bathtub "might" work if we 
could just figure out how to seal it!

Linseed oil is porous, though less than the highly absorbent clay.  Any 
water sitting on an oiled cob surface will eventually penetrate.  This 
will ultimately result in the decomposition of the straw which holds 
cob together and finally the failure of the cob bathtub.  We observe 
this water penetration in our very well oiled and beeswaxed cob 
benches, where pooled rainwater eventually soaks into the bench.

Now, if your tub was outside on a back stoop, perhaps no problem with 
the gradual seepage and eventual failure of the material.  But if you 
built the tub inside, you might be sorry when the tub fails and a 
mini-tsunami of warm bathwater floods your interior space!

So the debate is about how to seal our cob bathtub with something much 
more impermeable and probably more "unnatural" than linseed - asphalt 
emulsion, portland cement (?not so sure, since this is porous too!), 
Varathane or other acrylic compounds, latex, ???

I vote for taking an old cast iron, ceramic lined tub and encasing it 
in well oiled and waxed cob surroundings.  I still don't know if I'd 
trust this peripheral cob to resist the constant soaking of a tub 
environment, but at least I wouldn't have to worry about the failure 
and flood of 100 gallons of warm water into my house.

Ocean Liff-Anderson
_____

Steward, Ahimsa Sanctuary  http://www.peacemaking.org
Proprietor, Intaba's Kitchen  http://www.intabas.com


On Mar 26, 2005, at 6:20 PM, Amanda Peck wrote:

>
> a) because it's there.  (the more reasonable one IMHO)
>
> b) because it proves that cob is worthy of being a construction 
> material.   (like 6 or 7 hundred years hasn't already proved that)
> ..............
> Joe R. Dupont wants to know (right heavily snipped):
> Why is this insistance to make a cob bathtub?
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