Linseed oil has been popular and widely-used in finishing woodwork. It shares the properties of stains, preservatives and varnishes, and rolls them all into one. It is categorized as a 'drying oil', which means it dries and becomes a durable coating, and its propensity to sink in and be absorbed by almost any natural material it is applied to, helps to toughen surfaces by penetrating and then hardening even in the layers beneath the surface.
     Although it's not a stain, its natural color and wet-look bring out an especially prized natural beauty in wood products, so it is used on wood furniture (both indoor and outdoor furniture), deck floors, rifle stocks (handles), carvings, and is also used on other porous surfaces such as stonework and concrete.
     However, with increasing demands for certain qualities and properties in our substances these days, linseed oil in its original pure forms is almost never used; instead, it is mixed with a whole variety of additives to give it certain behaviors; for example, you don't want to use straight linseed oil to coat outdoor wood such as decks, because it takes so long (weeks and months) to dry. Also, being a plant-derived oil, it is prone to attracting mildew... so even though it helps to waterproof surfaces, the linseed oil itself will be attacked by mildew. Further, though it does create a hard, protective coating, it can never be applied in such thickness as a proper varnish, and so won't give the same amount of protection against scratches, damage and stains, and a too-thick application of coatings will seem to never dry, becoming a sticky, unattractive layer.
     So additives are used extensively, and for many uses synthetic products have completely pushed out the old reliable linseed oil.

 Its benefits can't be entirely synthesized, however, and you'll still see linseed oil being used widely by old-and new-timers alike, for gentle finishing and preservation of wood products. A lot of us just love that 'sentimental', earthy use of it, without all the new-fangled synthetics. And it will always be valuable as an additive to other products. It truly is a wonderful and versatile elixer, and I hope you'll appreciate using it in its natural form at least once in your life, in a form without the toxic additives that answer the call of the intense 'new world' demands.
     Corny as it sounds, there's a personal reward to getting your hands sticky with a linseed oiled rag, rubbing away on some piece of wood you're finishing, smelling that unique aroma passed down the ages through crafting hands.
    The pictures below: 1. Linseed oil has been applied to all things wood for hundreds of years: wooden instruments, paddles and boats, carvings, tool handles, flooring, to name a few. 2. Linseed oil for wood finishing usually comes in large cans like these; it's more watery than that used for oil painting, so can be applied more liberally for helping to weatherproof large surface areas, and also used as a paint thinner. These are two products by makers Geocel and Klean-strip.