The science of non-stick

[Ceefer]

Ok, I've got this really crappy stainless steel frying pan that I bought for use on an outdoor range when camping. It cost very little and has been badly abused over the years but the great thing about it is, in general, food doesn't seem to stick to it too badly. I've also got this very expensive frying pan manufactured in Iceland with a black non-stick finish which is generally pretty good but which some food, especially eggs, sticks to very badly. There doesn't seen to be any rhyme or reason to it - sometimes the food sticks and sometimes it doesn't.

So, what causes food to stick to a pan? What can you do to reduce sticking? Does it help to get the pan very hot before putting the oil/fat in? (I think it does). What is this 'seasoning' of a pan that I've read about, what does it actually do? Any scientists out there with the low-down?

[Bindibadgi]

The black stuff is PTFE, teflon, should be completely non-stick and inert to everything you chuck on it. Dont stick it in the dishwasher if you can help it or use sharp objects on it. As for what does and what doesnt, nothing's perfect and i spose it depends on the grade of PTFE and what you're cooking??

[Proplus]

Originally Posted by Ceefer

What can you do to reduce sticking? Does it help to get the pan very hot before putting the oil/fat in? (I think it does). What is this 'seasoning' of a pan that I've read about, what does it actually do? Any scientists out there with the low-down?

Yes, heating the pan up to a very high temp and then putting the oil in will help reduce sticking.

As for seasoning, the way I've been taught for the woks I got back at home is that after cleaning the wok to heat it up, and then place a drop of oil into it (off the stove), and smear it around to wok with a piece of kitchen roll....then store away.

[starside]

PTFE = Poly tetra fluoro ethylene.

[Nick]

Here’s the way I’ve always done it… this ONLY works for pans that aren’t non-stick… so stainless steel, black iron, even those Le Creuset enamelled pans are fine for this method.

Give the pan a thorough wash and clean, even using a steel scourer if need be.

Dry well and place over a high flame.

Add enough fine table salt to give a thin, even layer across the entire surface of the pan. You’ll find that you can only get so far up the edge of the pan, but go as far as you can.

Turn the heat down to a medium flame and leave the pan to cook.

After about 10 minutes, take a thick wad of kitchen towel, remove the pan from the heat and scrub the salt around the inside of the pan. BE VERY CAREFUL AS THE SALT IS VERY HOT!!

Spread the salt evenly over the base of the pan again and cook for another ten minutes.

Now tip the salt out of the pan, wipe round with a thick wad of kitchen roll, then allow the pan to cool for a couple of minutes as it will be very, very hot.

With the pan still hot, add a couple of tablespoons of vegetable oil and wipe round with kitchen roll. (Do not use olive oil as this burns at a low temperature, blended vegetable oils can tolerate much higher temperatures)

Your pan is now ready to use.

Note: When tipping out the salt, DO NOT tip it straight into the bin. The salt is very hot and will melt through your bin liner and, if its plastic, it’ll melt through your bin too! Don’t tip the salt into the sink either. If there’s water in the sink, it’ll steam up something rotten and you’ll get water vapour in the pan…. the very thing you’ve been cooking out… If the sink is empty, you risk cracking the enamel (if its an enamelled sink), or, as most waste plumbing is plastic, you risk melting the waste pipe under the sink. The best thing to do is to tip the salt into an empty roasting tin, let it cool down and then chuck it in the bin.

Cleaning:

Now you’ve gone through all the trouble of proving the pan, it’s important to clean it properly.

ALWAYS clean the pan while it is still fairly hot. I don’t mean scorching hot, straight from the stove, but at the same time, don’t let it go cold with food residue still in it. NEVER immerse the pan in water to clean it. Using a washing up sponge or dish cloth, dip the sponge in warm soapy water and gently wipe round the inside of the pan. Lightly rub over any stuck on food to remove it. Dry the pan with a tea towel straight after washing, then lightly oil it before putting away for next time.

Taking care of a wok is slightly different. You still prove it in the same way, wash and dry it the same. But before oiling it, place it over a high heat for a few minutes and let it get very hot. Now let it cool enough to re-oil and then its ready to go again.

[Ceefer]

Thanks Deckard, that's lots of good detail. Do you know what the salt actually does? Is there some sort of chemical reaction during the 'proving' process? Can the salt be saved and re-used?

[stytagm]

Just an aside on PTFE,

When I had a student job at a research company making things like radar antennas and satelite dishes, they were experimenting with radomes (covers) for flat panel, slotted, phased array radar antennas, which roughly explained lookes like a flat collander.

They would merilly bond ptfe onto these things, and then when the properties wern't quite right muggins here had to spend days scraping the things off again. And of course there isn't a chemical cleaner that can dissolve the stuff as it's so inert, and I often had to scrape, cut and abrade the things off with scapel blades. I wasn't allowed to sand them off for fear of damaging the antenna or getting debris in the slots.

So my question is this: How come my marks and spencer Milk pan started losing it's s*dd1ng coating after three days? Despite being treated /ever/so gently with a wooden sppon etc.

[funnelhead]

cos marks and spencer use woodglue to stick the teflon down.

[Rob]

Originally Posted by stytagm

So my question is this: How come my marks and spencer Milk pan started losing it's s*dd1ng coating after three days? Despite being treated /ever/so gently with a wooden sppon etc.

Cos they didn't do this...

The bottom line was that the non-stick didn't stick to the pan long enough. So, back to the drawing board.

The basic non-stick molecule is a polymer, or chain, of fluorine atoms and additives such as carbon and hydrogen. The longer this chain, the tougher it is; but a molecule that's too long gets viscous and hard to handle.

To move beyond mere mechanics, the frying-pan engineers added a sticky molecule to the non-stick molecule. Non-stick was now applied in coats, with the bottom coat containing the sticky additive that held to both the metal pan and the non-stick molecules. A coat of non-sticky non-stick went over that, non-stick and non-stick clinging together lovingly. A final non-stick layer, spiked with teensy bits of ceramic or other tougheners, protected the softer guts.

This is how lots of non-sticks are made still: Grit-blast the pan; spray on a sticky primer coat, a midcoat, and a tougher top coat; and bake. Oh, yeah: Add colors if you like -- the fluoropolymer is naturally white, but cooks prefer somber saucepans. You may also add a handful of mica, a sparkly rock, to glimmer up the finish.

Taken from HERE