I've been using a 1-1-1 combination of linseed oil, non-poly varnish, and turpentine or mineral spirits for a finish as of late. I apply the mixture with my fingers and work it in until the stock won't take any more. Leave it set until dry as long as there are no puddles. If you do get one, work it in or blot it up. Once fully dry, I repeat the process another couple of times. THev more you hand rub, the better it will be.
Solvent fumes are not good. I quit using anything with these as a component years ago. The problem with store bought “boiled” LS oil is that its not stock finish, it basically log oil for painting fences and log buildings/oil paint thinner and it dries too slow. This can be corrected by buying a gallon of “boiled” oil, a second hand store deep fat fried (or electric skillet) or two, some Japan drier and some calcium carbonate pills/powder from a health food store, crushed limestone will also work. Put the oil in the fryer or skillet, add a tablespoon or 2 of japan drier (I do a gallon at a time) a hand full of calcium pills, dozen or so. Turn it on high and leave till it starts to smoke a little. This does several things, it thickens the oil and darkens it, it kills the organic acids (as the oil warms it will start to bubble as the acid is reduced by the calcium, like putting acid in baking soda) which can inhibit drying. The added driers will speed drying a little more. The “boiled” on the label just means its had driers added so it will polymerize faster. Heating it will thicken the oil somewhat (this is a good thing for stock finish) darken it, another good thing and it will also “dry” faster.
BUT its going to waterspot, get white when exposed to high levels of moisture etc. Its a good filler but not the best top coat. The cheap and easy way is to mix your heat modified oil with Birchwood Casey Tru-Oil about 50-50.
The best way is the follow Eric Kettenburg’s varnish recipe. But I could not make the alcohol dissolved resin thing work and finally mixed them slowly into heated Turpentine. BUT DO NOT HEAT TILL IT SMOKES. Hot but not that hot. Its got a far lower auto ignite temp than LS oil. Once the resins are combined add to hot oil a little at a time until its all in or if the pot is big enough add hot oil to the turp-resin mix. This makes a really nice traditional finish that I really like. If its a little thick for a seal coat at 5-10% turp than has been aged 2-3 days in a shallow pan open to the air. It works better that way. The heat bodied oil/oil varnish will fill American Walnut if far fewer coats than the thin, mostly solvent “modern” finishes will and if made right this varnish will be hard enough the rub back/recoat in 12-24 hours at 65-70 degrees. Direct sunlight will kick the varnish over much faster but heating the stock will force a little out of the pores and may need to be wipes soon after put in the sun. With sunlight 2 coats a day can be used and I done a filled finish in 2-3 days on American Walnut when done rifle. But I generally used just heat modified oil for fill. I allow this to set in a open jar with a cloth over it ti partly gel this makes a very thick fill that can be put heavily on the stock by rubbing it on, left till partly set, surface will wrinkle, then rubbed back to the wood with burlap and recoated. In summer 2 coats a day can be used. But take it all off with the burlap rub before another coat. Then after the final rub add a thin coat of varnish rubbed on by hand. For shine. Be careful of spontaneous combustion or rags ect as with any drying oil/varnish.
This makes a fairly soft varnish that is easy to rub back but hard enough to look good and not waterspot easily if at all. This is essentially the varnish used by gunsmiths back in the day unless they used spirit varnish.
BUT BE CAREFUL. No kids or pets around, its like a deep fat frier cooking chicken or french fries serious serious burns can result so use protective clothing and BE CAREFUL. And do this OUTSIDE.
Finishes containing high levels of stoddard solvent etc dry mostly by evaporation of the solvent. Many are 80-90% solvent. Very little actual finish.
Do not use propane stoves or any open flame even an electric hot plate is iffy.
