Linseed oil is one of the best ways to preserve and finish wood. The challenge of working with linseed oil is its long drying time. A heavy coat of it can take days or even weeks to dry. To speed up drying time, start by purchasing boiled linseed oil. Boiled linseed oil has solvent thinners added to it to promote faster drying. You can speed up the drying time by adding more solvent and atomising the oil with a spray gun.
Fill the canister on the spray gun 3/4 full of linseed oil.
Pour in 1 cup of turpentine. Use a flat wooden stick to stir the mixture.
Plug the spray gun into an air nozzle. Turn the spray volume knob on the back of the spray gun counterclockwise until it stops, and then counterclockwise 1/4 turn.
Hold the gun about 8 inches away from a piece of scrap wood that is standing vertically, and spray a short burst of oil. You should see a light pattern of oil 12 inches long and 3 inches wide. Touch the pattern with your finger. It should feel damp, but not wet. If the oil is dripping, turn the flow control knob 1/8 turn clockwise and test again until the pattern is consistently damp without runs.
Spray the linseed oil across the surface of the wood that you want finished. Move quickly, spraying a band of oil in one direction and then coming back the other direction with another band of oil. Try not to overlap the bands of oil.
Check the oil after 20 minutes. If it feels dry to the touch, sand it lightly by hand with 180-grit sandpaper and spray on another coat of oil. If it feels damp, wait another 20 minutes and then sand and respray.
For the quickest drying times, make sure the room temperature is 22.2 degrees Celsius or higher. No matter what you do to linseed oil, it will not dry as rapidly as lacquer or varnish or produce a glossy finish like lacquer, but it does penetrate better. If you absolutely must have it dry faster than 20 minutes, add more turpentine to the oil, but be aware that thinning the oil also reduces its effectiveness.
Always wear breathing and eye protection when working with finishing products.