[SEL] Saw Outfit Blade finish/now linseed oil

[Robert L. Holtzer]

Try this site for linseed oil information

http://www.naturalhandyman.com/iip/infxtra/inflin.shtm

Bob Holtzer

At 06:10 PM 9/24/2004 -0400, you wrote:
>>I have a really dumb question. What really is "boiled" linseed oil?
>
>"Boiled Linseed Oil" is stuff that's sold under that name. There really 
>are two kinds and no easy way to tell what you've got. One is basically 
>raw linseed oil with Japan drier added to it to make it dry faster. The 
>makers used to use lead and copper soaps or naphthenates, but in more 
>recent years it has been usually the less toxic cobalt and manganese 
>naphthenates. (Naphthenic acids are petroleum derivatives, kind of like 
>fatty acids, but instead of straight chains they have saturated ring 
>hydrocarbon structures attached to the carboxylic groups. So these salts 
>are basically detergents, like soaps.) The metal ions promote free radical 
>formation stimulating the oxidative polymerization of the oil. The same 
>way metals from your babbitt bearings promote your engine oil sludging up 
>with heat and oxygen.
>
>The other kind is simply raw linseed oil that's heated modestly, to about 
>150-200°C, and air is blown through it till it reaches a certain point of 
>beginning oxidation without getting too thick and gummy for use. Since 
>linseed oil's oxidation is self-catalyzing once started, this stuff dries 
>much faster than raw linseed oil, which takes forever and a week. This 
>"boiled linseed oil" is essentially the same as the "stand oil" used by 
>artists for centuries, which is raw linseed oil left standing for months 
>in a clear glass jar exposed to sunlight, with some air exposure.
>
>I recently did a search for MSDSs on boiled linseed oil and looked for any 
>mention of metallic ingredients. My search wasn't exhaustive, but I looked 
>at a bunch of them and couldn't find any. So I think most of the BLO on 
>today's market is the preoxidized sort without metallic additives. That 
>fits with my observation that it initially dries pretty quickly but stays 
>in the gummy stage a lot longer than the leaded stuff used to.
>
>There is yet another product generically termed "polymerized linseed oil," 
>sold under brand names like Tru-Oil and Lin-Speed. (Some of the "Danish 
>Oils" fall into this category, too, while some of them are thin wiping 
>varnishes.) It's been cooked at a higher temperature that directly breaks 
>some of the double bonds in the fatty acids, which re-link with each 
>other, forming polymers without the oxidation. These oils are very fast 
>drying and dry to a hard, glossy shine like varnish. They're mostly sold 
>in small quantities for gunstock finishing, but are NOT the stuff to use 
>to get an old-fashioned oil finish on a stock.
>
>John Culp
>Bristol, Tennessee, USA
>
>
>_______________________________________________
>SEL mailing list
>SEL at lists.stationary-engine.com
>http://www.stationary-engine.com/mailman/listinfo/sel