[GSBN] earthen floor sealer in Haiti

[Derek Roff]

I don't know the book that Jorge mentions, but I have a couple of 
concerns about the quoted text.  First is a safety concern about the 
statement "Another option is to boil the boiled linseed oil".  Heating 
any oil should be done with extreme caution, and attempting to boil an 
oil will almost certainly cause a fire and/or severe burns to the skin. 
These might be pluses if one is defending a medieval castle from the 
invading Visigoths, but for floor work, heating oil via a heated water 
bath is much safer.  I suspect that most people on this list are 
familiar with the risks of spontaneous combustion from the rags or 
bushes used to apply the linseed oil, but this causes many fires each 
year.  Rags should be allowed to dry outside in a single layer, such 
has hung on a fence or clothesline.

Boiled linseed oil contains chemical "driers", which are frequently 
metallic salts.  They don't use lead anymore (or so they claim in the 
USA), and most of the driers are not volatile, but I favor avoiding 
toxins as much as practical.  Bill and Athena Steen discuss 
pre-processing raw linseed oil by leaving it in shallow pans in the 
sun, with a class covers, for several weeks.  This helps the raw 
linseed oil cure faster when it is applied to the floor.

Linseed oil itself gives off volatile organic compounds (VOCs) as it 
cures, and I find that I get sick to my stomach if I get much exposure. 
Most people don't have that problem.  In addition, the cheaper linseed 
oils usually have strong, objectionable odors.  And, of course, 
solvents have lots of VOCs.  Commercially available citrus solvents 
frequently contain various petrochemicals, and I don't agree with the 
quoted text below that they are a more environmentally friendly choice. 
It's really hard to say, without picking specific products.  Care is 
needed in any case with solvents.  I believe that turpentine from trees 
is generally safer and more pleasant than the commonly substituted 
mineral spirits, derived from petrochemicals.  Some people are more 
sensitive to turpentine than non-petrochemical citrus solvents, for 
others, it's the reverse.

Derelict

Derek Roff
Language Learning Center
Ortega Hall 129, MSC03-2100
University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek at unm.edu


--On Thursday, March 17, 2011 1:42 PM +0000 Van Krieken 
<vankrieken at gmail.com> wrote:

> There is a quite detailled chapter about earther floors in this book:
> Building with Cob, by Adam Weismann & Kathy Brice.
> I sugest you get this book, a great step-by-step guide.
>
> Concerning the sealant: (in page 172):
>
> «(...) In the past, animal urine and blood were used to acieve the
> sealant. These days it is more common to use boiled (NOT RAW) linseed
> oil mixed with a solvent such as turpentine, or citrus oils for a
> more enviromentally friendly option.
> The solvent acts to assist penetration of the oil deep into the pore
> spaces of the floor. Without it the oil will simply form a shell on
> the surface of the floor, wich will be easly broken and damage.
> Another option is to boil the boiled linseed oil, wich assists
> penetration of the oil into the floor and thus eliminates the need to
> add a thinner.
>
> The formula is as follows:
>
> 1st coat: 100% boiled linseed oil
> 2nd coat: 75% boiled linseed oil/25% thinner
> 3rd coat: 50% boiled linseed oil/50% thinner
> 4th coat: 25% boiled linseed oil/75% thinner
>
> Mix the oil and the solvent together in a bucket and apply evenly
> using a paintbrush
> Aloow each coat to dry between each aplication, and when the floor no
> longer feels tacky to the touch.
>
> Apply final beeswax polish.»
>
> Good  floors!
>
>
> Jorge Van Krieken