Sheryl Hatfield

Any smoking oil will give you a headache. You need very good ventilization when you do this. Once the polymerization is complete, the surface won't smoke.

Thanks for posting the chart, Ken. That's where I found it, too.

Yes, Jami, the smoke point for any oil is when it starts to release free radicals. That's why you never should heat oil for cooking so hot that it smokes, and if you do it by accident you should throw it away (unless you're seasoning a cast iron pan, of course).

The reason this chart was posted on Cooking for Engineers is so people would know which oils were safe for cooking and which were not. Here's the beginning of that article:

http://www.cookingforengineers.com/article/50/Smoke-Points-of-Various-Fats

The smoke point of various fats is important to note because a fat is no longer good for consumption after it has exceeded its smoke point and has begun to break down. Once a fat starts to smoke, it usually will emit a harsh smell and fill the air with smoke. In addition it is believed that fats that have gone past their smoke points contain a large quantity of free radicals which contibute to risk of cancer.

You never ever never want to use flax oil for cooking. Polymerization is for the pan, not for inside your body. Free radicals inside your body are known to be carcinogenic. The smoke point is the point at which the free radicals are released. Flaxseed oil has a very low smoke point. Never cook with it, and keep it in the refrigerator.

That is awesome to hear. Thank you for posting this! (I'm Sheryl.)

Of course you want to use food-grade flaxseed oil (from a health food store), not the linseed oil that a hardware store sells.

I've only seen the "webby" thing when I used bacon fat, and I think that happened because there are non-oil things in it - salt, notably, and who knows what else.

"Free radicals" have to do with molecular chemistry - unstable molecules emitting electrons until they are stable. It's a chemical reaction that causes the molecule to change into something else.

Hematite is red rust. Magnetite is black rust. Both are "rust" because they're formed by oxidizing iron. I explained it in my blog post.

http://sherylcanter.com/wordpress/2010/02/black-rust-and-cast-iron-seasoning/

I'm done buying cast iron myself. I have everything I need now.

paul wheaton wrote:So, at cooking temperatures, any oil will polymerize, right?

Not at cooking temperatures, at smoking temperatures. You never want to eat oil you've allowed to smoke because it's releasing free radicals, which are carcinogenic. For this same reason, you need oil to smoke for it to polymerize. When it's fully polymerized and no longer releasing free radicals, it's chemically stable again and no longer carcinogenic. It's not oil anymore, it's a polymer.

But not all oils polymerize equally. Someone posted a comment to my blog post that adds some info on this:

http://sherylcanter.com/wordpress/2010/01/a-science-based-technique-for-seasoning-cast-iron/#comment-298

paul wheaton wrote:I know that I have had times where fats will leave a polymerized layer that is a thin, contiguous layer. And other times where fats will leave a layer that is "mottled" or "spider-web-ish".

I've noticed this only with bacon drippings, which contain a lot of ingredients that don't polymerize - notably salt.

I also have discovered that heating the pan first, to create a thin layer of magnetite, improves adherence and slickness:

http://sherylcanter.com/wordpress/2010/02/black-rust-and-cast-iron-seasoning/

I wish I'd heated my skillets first. Maybe at some point I'll strip them down and do that, but they are perfectly serviceable as is.

It's not exactly that rancidity = polymerization. The type of polymerization that occurs with cast iron seasoning is called "radical polymerization", and this is initiated by the release of free radicals in the oil. The release of free radicals in the oil is also what defines rancidity. So more accurately, rancidity = initiation of radical polymerization.

You modified a part of the code that I found too complicated to touch, although there is a bug in there that drives my forum members and me crazy. If you type multiple spaces in a row (as people often do between sentences), you get question marks. I took a quick look at the code to see if I could fix it, and it made my eyes cross so we live with it. Did you fix that? I'll type a few spaces here and see what happens:      space-space   

I'm running a fork of SMF 1.1 Beta 3 - a little later than what you have here.

(Apologies for going off topic.)

Interesting, thanks. I guess that puts me at Level 3 (except I no longer have an organic garden because I live in NYC).

paul wheaton wrote:
For a clue, take a look at my much bigger website, JavaRanch.

It's Java?? Now I'm really confused. SMF is written in PHP, which I know because I wrote a fork to support paid subscriptions for my own site (http://normaleating.com). I also added the ability to moderate posts, though this turned out to be unnecessary once the forum became fee-based. Trolls don't pay for the privilege to be nasty. The forum is also now a one-time fee instead of a monthly fee, so I did a lot of unnecessary programming, but I digress. How did you integrate SMF with Java?

I don't know much Java, but I'm very strong with PHP and moderately okay with JavaScript.