Linseed Oil For Varnish

[Joe S]

What kind of linseed oil are you using to make varnish?  There are many different kinds of linseed oil available, and I’m wondering if anyone knows what they are and what is best for a traditional varnish.  Cold pressed oil seems to be pure pressed oil, with no additives or further processing.  How is that different from raw linseed oil?   Is the raw linseed oil in the heath food store the same as raw linseed oil you would find at the hardware store or in an art supply store?

On the http://www.woodfinishingenterprises.com/coating.html site, I find Varnish Makers Linseed Oil, which  “has been refined to remove the “break” so that it will not become cloudy on heating to make varnish.”  What is that all about?

Prices are all over the place too.  Raw linseed oil runs about $20 per gallon, while you can also find a Dutch oil that had been pressed in a real windmill for over $400 per gallon.

Much to my surprise, I found linseed oil that has been heated with lead at http://www.jerrysartarama.com/discount-art-supplies/Oil-Color-Paints-and-Mediums/Williamsburg-Oil-Paints-and-Mediums/Williamsburg-Oil-Painting-Mediums.htm?utm_source=froogle&utm_medium=cpc&GCID=C12646x001

There seems to be general agreement that refined oils make a more brittle, less durable varnish, but beyond that, I have not been able to find any information that would help me select an oil.

[LynnC]

Joe,
I think Eric Kettenburg has written a ton about varnish making and boiled oil on his website.
Perhaps he'll reply ........................Lynn

[erdillonjr]

 I use boild linseed oit with the first coat mixed 50-50 with turpintine. The rest of the coats are stright linseed. Just a finger full rubbed in till the stock gets a little warm from rubbing. steel wool with 4/0 steel wool after each coat is dry. Ed

[Joe S]

I asked Eric what he was using, here’s his reply:

Joe I start with plain old raw pressed oil.  I bought a LOT a few years back through Kremer in NYC when they were having a blowout on some off brand of German stuff.  Has worked well for me.  There is more expensive Swedish oil out there which is more refined (not via chemicals) and cleaner but it's a whole lot more money.  I have no idea what's in the hardware store stuff but frankly it usually smells kind of rancid.

I’m curious what other people are doing, and I’d also like to know if anyone knows what all these types of oil are, and whether or not they are suitable for varnish.  People tend to talk about how the boiled their oil, but never seem to say much about what it was that they were boiling.

[LynnC]

The oil I have boiled was store bought name brand stuff.  But it was probably 30 or 40 or more years old from the advertising on the can.  It makes good dark red oil.

I have a gallon of near new oil but havn't made any boiled oil from it yet.  Plenty of the old stuff on hand.

From what I've read,  That older oil I boiled ain't much different than todays oil.  It's not really boiled at all - just driers blended in.

I think you have to go way back to get real boiled oil.  Then you wouldn't need to boil your own in the first place.

So - Use what store bought stuff you can get IMHO. ...................Lynn

[Stophel]

I've been using the "Varnish maker's oil".  It's a good quality clean oil, that has been working quite well for me.

[Joe S]

I have learned something about the “break” that has been removed from the Varnish Maker’s Oil.  This is from the May 1903 Journal of The American Chemical Society (courtesy of Google Books).

“Freshly pressed linseed oil, or linseed oil that has not been properly settled or prepared for the manufacture of varnish, when heated to, say, 400 degrees Fahrenheit, undergoes a change which the varnish man describes as “breaking”.  The phenomena consists in the appearance in the oil of gelatinous masses slightly darker than the oil itself, settling with difficulty, and extremely difficult to remove from the oil by filtration.  The bulk of the break appears in some instances to be considerable.

….the principal cause of the break in the linseed oil is the phosphates of lime and magnesia present, although their presence in the oil may be due to a combination between them and some organic base or bases.”

So the substances that cause the “gelatinous masses” can apparently be removed by settling.  I wonder if this is the same material that is removed these days by bleaching and other chemical treatments in use today.  Settling requires at least some patience, not a commodity easily found in American manufacturing.