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Polymerized Linseed Oil vs Boiled Linseed Oil
Choosing the right type of linseed oil can be overwhelming due to common misconceptions about what is natural and what contains potentially harmful chemicals. One of the most confusing terms is "boiled" linseed oil, which isn't simply heated but actually polymerized with chemicals. On the other hand, "polymerized" or "heat-bodied" linseed oil undergoes polymerization through heat, without the addition of chemicals and is 100% natural. Products labeled as "pure," "raw," or simply "flaxseed oil" are cold-pressed and natural but may not cure efficiently on their own, making them less ideal for woodworking applications.

Differences in Linseed Oil, the Safest and Best for Woodworking

Polymerized Linseed Oil
Polymerized Linseed Oil - Polymerized Linseed Oil, the variety Walrus Oil offers, is made by heat-bodying raw linseed oil to accelerate the natural oxidation and polymerization. This method enhances the oil's durability and water protective qualities, increases the sheen, and helps the product dry faster when applied to wood, in some cases it cures in a matter of days. Polymerized linseed oil typically yields a matte or satin finish, which is valued in fine woodworking and furniture finishing for its durable yet less glass-like appearance. Since there are absolutely no drying agents or solvents added to polymerized linseed oil, it is considered "all natural", can be safely used on food-contact surfaces, and respiration masks and ventilation is not required since it's also VOC-free. For these reasons, it's become the most favored of all linseed oil options for woodworkers, makers, and even retailers. To clarify, Polymerized Linseed Oil is processed by only heat, with no additives, which is quite the opposite to Boiled Linseed Oil.

Boiled Linseed Oil, aka BLO - Boiled linseed oil is processed with metallic drying agents like lead, cobalt, zinc or manganese, and sometimes includes added solvents, to quicken the drying process. This treatment gives boiled linseed oil a faster drying time compared to raw linseed oil and influences a glossy finish when applied to wood, making it popular as an ingredient in oil-based paints and coatings. However, with the addition of drying agents and some solvents, boiled linseed oil is typically not considered "all natural", it cannot be used on food-contact surfaces, is toxic if accidentally ingested, and requires special respiration masks and ventilation while being applied. The VOCs also make the product difficult to ship, which is why many retailers are pulling BLO from their shelves.

linseed plant flax
Raw Linseed Oil, aka. Flaxseed Oil - Raw linseed oil, derived from cold-pressing the seeds of the flax plant (Linum usitatissimum), is characterized by its natural pale yellow to amber color and thick, viscous consistency. Though natural it does have several drawbacks compared to polymerized linseed oil. It can take many weeks to cure, it's not nearly as durable as Polymerized Linseed Oil or Tung Oil, and offers much-less protection from water and abrasion.

To summarize, if choosing between Raw Linseed Oil, Polymerized Linseed Oil, or Boiled Linseed Oil (BLO), the safest option that provides exceptional protection to wood is Polymerized Linseed Oil. The extremely thick consistency of Polymerized Linseed Oil will however require a little effort to apply to raw wood surfaces and some may prefer to cut it with a thinner oil like Tung Oil or a natural solvent to lower it's viscosity for better penetration.

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