Could you please expound on this more or let us know where to get this information?
The USA boiled linseed oil can be made into a decent stock finish by re-cooking in the presence of limestone and adding a little more drier.
Adding limestone when re-cooking it will kill the organic acids and helps speed the drying.
Mad Monk would be the one to answer this question.
If you search for posts on linseed oil you will find details on making boiled oil. But I have no idea if "Japan Drier" for example is available in Europe.
Dan
I have gone over it several times on this site.
Dump a gallon of "boiled" oil in old deep fat fryer, add some limestone or even calcium carbonate, I use some limestone pebbles about the size of my thumb 3-4 is enough, whack them with a hammer a couple of times and put all the resulting limestone in the pot. Add a tablespoon or so of japan drier, though "boiled oil" as purchased has driers added. Set fryer on high and wait. As the oil heats it will react with the limestone and bubble for awhile.
When it reaches max temp the oil will smoke. Leave here for 1/2 or so then let cool. Decant 1/2 the oil into pint jars and then cook the rest again for a hour or more to make thicker bodied oil. The lighter oil will also make oil cloth without rotting the fabric as is most likely the outcome with off the shelf "boiled" linseed since its pretty acidic. Why the calcium carbonate is added to the pot.
The oil can be further thickened by covering a 1/2 full pint jar with a cloth to allow the oil to thicken. it will skin over and get very thick but will still work well for fill on walnut when too thick to drip off a finger. Cut the skin and dip out what is needed.
There are other things that can be added to this to make oil varnishes. For top coats I mix the oil with Grumbachers Oil Painters Medium III this makes a very durable finish that will not water spot and has nothing "new" in it but some D-limonene. This can be left outside all fall and winter in MT with no checking, pealing etc.
I have been playing around with re-cooking (the oil never really boils in a deep fat frier) with the Grumbachers and natural pigment burnt umber and burnt sienna (oil painters colors). It will give this color and a shine if simply painted on maple with no stain. The pigments do not combine well cold in my experience
I think with some experimentation it would make a single pass finish for plain maple etc for barn guns and such though it does little for the curl. It seems it will even "level" scraped wood that has not even had the grain raised. I think it should be possible to scrape the stock smooth then paint/wipe on the finish and after a few hours in direct sun or indoors for a couple of days in winter the gun would be ready for use.
What I do in stock finishes is based on information Mad Monk sent me years back. He knows far more that I.
Dan
