[Cob] Re: oiling cob

[paul]

----- Original Message ----- 
From: "Barbara Roemer & Glenn Miller" <roemiller at infostations.net>
To: <coblist at deatech.com>
Sent: Monday, February 05, 2007 10:13 PM
Subject: [Cob] Re: oiling cob


> Maybe the answer to how and whether and with what to oil cob is more 
> complex
> than it seems on the surface.  I have oiled exterior cob walls to give a
> little more weather resistance in our climate and had no rancid smell -
> none, ever.  But we used cheap linseed oil with heavy metal driers.  The
> smell soon dissipates, which means the particles are volatilized and drift
> off to join the rest of the goo in the air - bad news.  I live in a 
> heating
> climate - cool, rainy winter.  While we normally have about 65" of 
> rainfall,
> we also usually have only three days of overcast before it's sunny.  Our
> summers are hot and bone dry from May to October.  Maybe it's our 
> relatively
> "dry" climate - that is, low humidity, concentrated periods of rainfall
> alternating with sunshine, and hot dry summers - that keeps oiled cob from
> molding here.
>
> I have oiled our earthen floor on three different occasions in four years,
> with many coats each time.  I used low voc products from green suppliers 
> who
> state their products use citrus thinners and no heavy metal drying agents.
> The smell lasts for about three days (done in summer and fall), and I'm 
> very
> sensitive to it, so would recognize if it went rancid or smelled longer 
> than
> that.  I've used Hard Oil #9 along with beeswax, and had very little smell
> even after the first day.  While our floor is not heated, during the 
> coldest
> parts of winter we set up a little heater in the bathroom, and the floor
> gets quite warm and stays that way for hours.  It never smells or gets
> rancid.  If you don't apply too much oil, it shouldn't sit on the surface
> and be concentrated enough in any one place to go off.
>
> Bill Steen, on the S-B-R-Us Yahoo list, of the Canelo Project outside of
> Tucson, where there is about 12" of rainfall annually, has been putting in
> earthen floors and oiling them for about 15 years.  He is about to publish 
> a
> long-awaited revision to his original floor book (pretty much ignore much 
> of
> the first one).  He dries raw linseed oil out in the sun in thin layers in
> cafeteria trays and then oils his floor.  No driers, and usually now no
> thinners, I believe, although for years, he cut the oil with turpentine, 
> and
> I've never smelled any residue in his buildings.  I was not there
> immediately after any oiling, though. Bill posted recently about how his
> floors have held up over the years, so anyone with interest can check out
> the SB archives, or soon, buy an e-copy of his new floors book on his
> website: <caneloproject.com>  .
>
> On the downside, I've seen both oiled and unoiled cob walls on the moist,
> temperate California coast with a shaggy fungal coat.  Even dirt will mold
> under the right conditions - usually warmth & moisture together.  It's the
> organic material in the soil being broken down by decomposers.  My
> experiences are limited but it seems that mold has more to do with 
> climate,
> and rancidity with heavy applications that can't be absorbed by the cob.
> I've mixed oil into clay, both for walls and floors, and then oiled it
> afterward, with no ill effects. I'd like more info from those of you with 
> an
> experience of mold or rancidity - what are the local conditions?
>
> 23 cents' worth Barbara

Thanks for the 23 cents' worth, Barbara.  I think that new book is going to 
be a "must".

BTW, the house I was in that was ready to drive the inhabitants out was in 
the mountains of NC (Ashville) and had been a mixture of oil and turpentine. 
The exact type of oil (meaning boiled/chemicalized versus raw) is not known. 
It must have been the worst possible combination because it stank 
noticeably.  Unfortunately there seems to be so many variations on the theme 
that we need to know what questions to ask before we even know what somebody 
applied.  "Linseed" isn't a very exact answer.

Also, "how" they applied it could end up being meaningful:  Too heavy could 
cause problems that prevent drying.  If somebody is applying chemicalized 
linseed and not even allowing drying, then it may outgas for a very long 
time.

Also, the climate and radiant heating all seem to have an effect.  It's 
incredible how many variations there are.  We need that book.

p