Buy a gallon of boiled oil, I prefer Parks brand if it can be found and some Japan Drier.
Buy an old deep fat fryer at a second hand store.
Pick up some limestone a few pebbles 3-4 about the size of my thumb work.
DO THIS OUTSIDE. It is fully as dangerous as a deep fat fryer used for cooking. Keep all living things away from it.
Put the oil in the fryer with the limestone after its been whacked with a hammer once or twice to make it finer.
Put in a tablespoon or so of Japan Drier.
Put the fryer on high. Oil will begin to smoke when near max temp. Keep it there for 10-20 minutes then shut off and allow to cool. This will darken and thicken the oil.
Decant into jars.
For fill oil for walnut I leave about 1/2 the oil in the cooker and reheat for an hour or so to thicken it more.
The limestone reduces the acid level in the oil to reduce drying time. This oil can be used to make HC oil cloth too but the acids will rot the cloth so acid reduction is important.
Some add lead acetate etc to the oil to redden it somewhat and reduce drying time in high humidity.
On walnut this oil will allow 2 coats a day if put in direct sunlight. I apply heavy for walnut then rub off the excess to fill the grain. 0000 steel wool will work on uncarved guns. Take it off when it get rubbery and will not pull from the grain. This stuff will work as fill when very thick and I put a cloth over a pint of it to allow air access to thicken it more.
It will also enhance the figure in wood far better than modern clear finishes will.
Initial coat should be the thin oil with 1 in 4 parts (+-) turpentine that has been aged in a shallow pan 2-3 days to allow it to pickup oxygen. This will speed drying of the oil that soaks into the wood.
I mix the oil 50-50 with Grumbacher's Oil Painting Medium III for final stock finish. Makes a soft oil varnish than resists water better than straight oil. I do not do built up finishes.
Dan
