[Cob] Drying of linseed oil

[Amanda Peck]

Thanks for those.

The woman who has been writing about her vertical log cabin for at least two 
of the magazines lost the first version because she left an old t-shirt that 
she had been using to wipe linseed oil on with wadded up on the porch.  
Spontaneous combustion is a real possibility, and if "boiled" should have 
been in quotes in the 30's may have been what my mother was warning about.

I also found this, which only makes me more confused than ever!:

http://www.noteaccess.com/MATERIALS/RawL.htm

Raw  Linseed Oil

When the linseed is steam-heated before it is pressed, it yields more oil 
than it does when cold-pressed, but this oil is darker and inferior to the 
cold-pressed product in color stability, drying rate, and film-forming 
quality. Such steam-pressed oil may be left to stand in a tank until it 
throws off impurities or mucilage, and so becomes somewhat clearer. Yet it 
remains much darker than cold-pressed oil and is much inferior to it as an 
artist's material. Marketed as raw linseed oil, it is used in furniture 
finishing and in cheap house paints. It may be identified by its 
comparatively sharp odor and taste. [p. 33]


..................
Quinn wrote (snipped a bit):

Finishing oil for cob--

A little bit about linseed oil:    
(http://www.wwch.org/Technique/FinishesRL/OilFin.htm)

Originally, boiled linseed oil was the material of choice, and it was 
typically
mixed with equal parts of thinner, such as turpentine, and occasionally
small amounts of varnish and/or bee's wax were added. Linseed oil
is an oil extracted from flax, and the term 'boiled' is misleading but very
important. Boiled linseed oil is not actually boiled, but rather oxygenated,
a process that changes the polymer structure of the oil, which causes it to
eventually dry and harden. Raw linseed oil will never dry, and does not
make a good finishing material. Even boiled linseed oil dries quite slowly,
and the addition of varnish or driers is common these days to speed drying
and provide faster build of the finish. Tung oil is another commonly
available finishing material, though more often than not, off-the-shelf tung
oil finishes are not true tung oil at all, but rather a mixture of the 
materials
I've previously mentioned. Tung oil has become a somewhat generic term,
encompassing many varieties of oil finishes.

And about tung oil:    (http://www.sutherlandwelles.com/tungoil.htm)


The Polymerized Tung Oil must be formulated with solvents to thin the oil to 
maximize its workability and penetration and driers to shorten the drying 
and curing time. Sutherland Welles Ltd.® has researched and implemented 
driers with the lowest toxicity available. We also use solvents that are 
"cleaner" reducing the environmental impact and minimizing a finisher's 
exposure to toxic fumes and chemicals.

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