Re: SB: Re: Smelly earthen floor (OT)

[Athena and Bill Steen <absteen@dakotacom.net>]

I just caught up on this discussion and apparently Barbara has gotten enough
good advice and hopefully it will take care of the problems at hand.
However, I thought I would add a few comments to the discussion about
Japanese clay work. First of all, the process described below involves the
use of rice straw and it is not certain that the same effects will be
achieved with other types of straw.  The other thing is that almost no one
uses that process any more because of the time involved and because the
resulting color is very dark and typically needs another finishing process.
I'm not so sure that the term "mold" describes what happens to the soil.  At
least from my understanding and observations of clays that we have stored in
a wet condition, it might be more accurately be described as an algal type
of growth.  Also, the rust appearing on the surface of the wall is more a
function of the type of soil used rather than the process of fermenting
straw with the soil.  The use of the word "cob" in this case is really a
stretch if it is being related to how it is practiced in this country.  The
mixes used are much wetter, applied rather thinly in comparison.  Lastly,
the tataki floors do not strictly use granite soils.  They also use clay
soils in combination with the lime.  Magnesium chloride makes a much better
floor than without it.  It is essentially the same as "nigari" which is used
to make tofu.  However, it is extremely difficult to get hold of at a price
that would make doing a floor out of it a practical option.

Bill
> 
> I thought Darel had mentioned that Japanese builders intentionally let straw
> ferment in their floors.  Though the chemistry of it still doesn't make
> sense to me, he explained further the process of gradually adding straw to
> the already fermenting straw in cob for use on walls:
> 
> "They don't put it in floors.
> 
> They use it for daubbing (cob) onto wattle walls.  Why they do this is
> because they feel that the lignin and pentose come out of the staw
> fibres and adds more stickiness to the mix and results in a harder
> resulting wall.   Note also that they don't do this to all of the
> straw.   They also feel that keeping the soil wet for a long time (up to
> a year or more for temples), three months average, but at minimum two
> weeks, is to let the iron in the soil oxydize and to let the organics in
> the soil float to the top and not used.   For the long soaking period
> they add the straw in not all at once in several additions.   The reason
> for this is said to be that the most fermented straws still have small
> fibres that grab the smaller clay particles and bind them together, and
> the lesser fermented and larger straw fibres then bind these together
> and so on until the newest straw added a day or two before application
> is then to hold all of the largest clumps together.
> 
> The Japanese mud masoners also say its important for the straw and soil
> to get used to each other: they begin to meld together and the soil
> changes color after soaking for three weeks.  The optimal length of time
> for soaking the soil prior to use depends on the temperatures, but one
> rule of thumb is at least until the soil changes color and black mold
> forms on it (this is the oxidized iron I think or rust from it).
> 
> For floors in Japan, from what I read, I hope to see some the end of
> this month, the (tataki) or tampered floors consisted of
> 1. a granite soil,
> 2. lime, 
> 3. water, ( with optional salt or Magnesium-chloride left over from
> salt making)
> 
> These ingrediengs where mixed in a semi-dry mix and then tamped/rammed
> down to about 50-67% of the before packed level.  This technique was
> used for entry and kitchen floors and sewer lines. and runs around the
> house and was in use until about 70 or 80 years ago in the country side.
> 
> They used this for some fence walls as well.  Sometimes they would put
> a vegetable oil in it to aid in water protection, but one has to not
> over due the oil part.
> 
> I was just using their wall daub mixtures as an example of the smell of
> fermenting rice straws."
> 
> 
> 
> I'd love to hear more on the daub and floor mixes from other Japanese
> builders.  Again, many thanks for the varied perspectives.
> 
> Barbara
> Nevada City, CA
> 
> 
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