The short answer
Refined coconut oil is flavorless and odorless, so nothing transfers to your food. It is high in saturated fat, so it resists going rancid and sticky. And it spreads in a thin, even film. That makes it well suited to protecting seasoning after every wash, while flaxseed oil builds the seasoning itself.
Seasoning and conditioning are different jobs
Seasoning is a hard layer of oil baked onto the iron in a hot oven. Flaxseed oil suits that job because it is a drying oil that sets hard: see how to season cast iron cookware.
Conditioning is the everyday step. After each wash you wipe on a thin layer of oil to keep moisture off the iron and protect the seasoning until you next cook. Refined coconut oil suits this job.
It adds no flavor or smell
Unrefined coconut oil tastes and smells of coconut. Refined coconut oil is virtually flavorless and odorless, so it won't carry into anything you cook, from fried eggs to seared steak.
It stays fresh
Refined coconut oil is high in saturated fat, which is stable and slow to oxidize. So it resists going rancid or turning sticky on the pan between uses, and it keeps at room temperature without refrigeration.
A thin layer is easy
Refined coconut oil is solid at cool room temperatures and melts on contact with a warm pan. That makes it easy to spread a thin, even film and hard to overdo it, and a thin film is what you want: thick layers leave a pan sticky.
It handles the heat
Refined coconut oil has a high smoke point, about 450°F (232°C), so a conditioned pan can go straight onto the stove without the film burning off first.
How to condition your pan
After every wash, dry the pan over low heat and let it cool a little. Wipe on a thin layer of Cast iron conditioner with a microfiber cloth. Preheat the pan for five minutes before you next cook.
Common questions
Can I season cast iron with coconut oil?
You can, but flaxseed oil builds a harder layer because it is a drying oil that sets hard in the oven. Use Cast iron oil to build seasoning and coconut oil to protect it between cooks.
How often should I condition my cast iron?
After every wash, while the pan is dry and still a little warm.
Is Cast iron conditioner vegan?
Yes. It is made from refined coconut oil and is vegan and vegetarian friendly.
