I know there are many oils that can be recommended/used for seasoning a cast iron. Recently I ran across Lodge A-SPRAY Seasoning Spray which is described as 100% canola oil. I am confused why this is product exists.
How is this significantly different than PAM canola oil spray? Will the aerosol in PAM ruin the seasoning somehow? Why buy the spray if I could just pour canola oil into the pan?
As you pointed out in your question, Lodge A-Spray is 100% canola oil. It is also in a non-aerosol container. Those two things mean that you have no added propellants or ingredients.
Most cooking sprays are not 100% oil. Most contain a additional ingredients, some of which would actually be a negative in trying to build your seasoning. Soy lecithin, for example, would create a quite tacky/sticky surface if allowed to build up. That would be quite the opposite of what you are trying to achieve.
As you note, there are many oils that work well in seasoning cast iron. Those sold in bottles work just as well as a 100% oil spray. And while typically the sprays are much more expensive, they are convenient.
Just remember that if you choose to use a spray, you always check the ingredient list to be sure it's 100% oil.
The spray is purely for convenience.
You usually cannot buy Canola Oil in small quantities (usually it's in a 16 oz or larger container), and it can spill/be messy. The dark metal sides of the spray bottle will also preserve the oil longer, since it doesn't allow light to penetrate and degrade the oil. If you keep your Canola Oil bottle in a dark cupboard, this wouldn't be an issue.
The spray helps prevent a mess, as you can control it a bit better, but it's entirely unnecessary and plain Canola Oil will do just fine. After all, it's what folks have been using for a very long time, well before the spray was invented.
I wouldn't use PAM Spray, it contains other ingredients other than Canola Oil. Mainly:
Most of the other ingredients will cook off when you season your pan - but using pure Canola Oil will be better for your pan.
Regarding seasoning your pan - I usually pour a generous amount of Canola Oil into the pan, knowing I can always wipe out any excess with paper towels.
