Economist Writing Every Day

I really don’t like the time and effort wasted in cleaning crudded-up frying pans, so I appreciate non-stick coatings. I have a small diameter Gotham ceramic pan that works well, and I was thinking of getting a larger one for cooking bigger loads. As usual, I went to the internet for wisdom on preferred ceramic pans to buy.

However, in the course of trying to get a fix on how they work, I fell down a rabbit hole. It turns out that this subject is complex and controversial. I will try to summarize my understanding in a brief post, with the caveat that I am not sure of everything here.

First of all, the “ceramic” coating is not really ceramic. Typical ceramics are made from firing powders of inorganic materials like silicon/aluminum oxides (including clays) at extremely high temperatures to where the particles fuse together. For the ceramic coatings on pans, this is not the case. I looked pretty hard on line without success to pin down the actual process or composition of the pan coating. It seems to involve some sort of silicone or silica polymer, applied using a sol-gel process. (Silica is just silicon and oxygen – quartz and white sand are pure silica – while silicone is typically a Si-O-Si-O-Si polymer with two extra hydrocarbon side groups attached to each Si).

100% silicone, in the form of rubbery sheets or cupcake papers for cooking on or in, is known to give a non-stick cooking surface. The “ceramic” coating in pans appears to be a solid equivalent of silicone cookware. A key factor mentioned in why it is slick and why it loses its slickness is that (supposedly) a thin layer of silica or silicone comes off with each cooking episode, and that thin layer is what gives the non-stick effect. (I would not mind ingesting a little adventitious silica, but eating random silicone worries me a little – but I don’t know if all this is actually true).

See this link for further discussion of the safety of ceramic versus teflon coatings. Be aware that makers of teflon coatings often choose names for their coatings that include the words “stone” or “granite”, perhaps to make the unwary consumer believe that these are ceramic coatings. My teflon pans have usually started to flake (into my food!) after a couple years’ use. A happy exception is a newer electric skillet which has temperature control so it never gets above about 425 F (high temperature destroys teflon). We do keep it oiled in use. Its teflon coating is still good as new after two years.

There seems to be general agreement that ceramic pans start off super slick, that fried eggs slide right out, but that after some months of use, food starts sticking noticeably. It helps to use a little oil every time you cook, and to avoid using metal utensils or abrasive cleaning pads, and to avoid very high temperatures or the use of cooking sprays (which deposit something harmful to the ceramic coating) or olive oil (which can burn on). Some users say it is important to clean the pan well between uses, e.g., using salt as a mild abrasive.

Why Do Ceramic Pans Lose Their Non-Stickiness?

There seem to be two main schools of thought as to the deterioration of performance. One school points to the (alleged) continual loss of silica particles or (presumably oily) silicone from the surface; perhaps once this surface layer is depleted, it’s game over. Another camp points to the buildup of burned-on deposits, even very thin, nearly invisible deposits, that then become a locus of food sticking.

What Can Be Done to Restore a Ceramic Pan Coating?

It is common to read that you just have to be prepared throw the pan away every 1-2 years. However, this does not seem economical. Can these pans be salvaged?  One author claims that slickness can be restored by “seasoning” a ceramic pan, similar to how cast-iron pans are treated: after cleaning the pan, rub a very thin layer of a recommended oil (e.g. soybean oil, not olive oil) on the pan and then heat it to the smoke point. This should bond a polymerized oil layer to the surface. I have not tried this, but it might be worth a try.

A diametrically opposite approach is recommended by the maker of GreenPan ceramic pans. Here the theory is that if an offending film of cooked-on crud is removed, the native, clean ceramic layer beneath will once again be non-stick. A wet Magic Eraser type cleaning pad is recommended.

A similar remedy touted on the internet (e.g. here and here) is to rub with coarse salt (for long time, but not too hard) to get down to a pristine ceramic surface. Good results are claimed.

As a (retired) experimental scientist, I was itching to try something like this. At a family member’s house, I found an older ceramic pan that was not in really bad shape, but had lost its primal non-stick.

The BEFORE picture is above. There was a persistent brown film in parts of the pan, and cooked omelets (my test vehicle) did not simply slide out. I cleaned the pan with soap and water and a sponge, then went at it with a wetted Magic Eraser. I got the brown film off, though you could still see some pitting in the coating due to the use of metal utensils.

The AFTER picture is below. This is after cooking yet another omelet (with oil), and just wiping the pan with paper towel afterward. I can’t say that it was a night and day difference, but the Magic Eraser treatment definitely seemed to improve the performance. Score one for sustainability.

APPENDIX:  Finally Understanding What Make Ceramic Pan Coatings Non-Stick

As noted in the original article above, I was puzzled over how the ceramic coatings worked. The descriptions in articles I could find on-line talked of forming these coatings from sol-gel solutions, using ingredients such as tetraethoxysilane. Without going into details, my chemical intuition led me to believe that, yes, you could form a dense silica pan coating from that, but the final outer surface would have Si-OH groups, like quartz or glass or ordinary “enamel” ceramic pan coatings. This would not give the oily, silicone-like surface that is evident with the nonstick ceramic pan coatings.

My “Aha” moment came when examining a patent application ( United States Patent Application No. 20180170815) for making a GreenPan ceramic pan coating. Among the ingredients for making the coating is methyltrimethoxysilane (MTMS).  And THAT should give Si-CH3 groups on the outer surface, which is exactly the type of oil-like outer surface that silicone has.  (The -CH3 methyl group is a fairly nonpolar, “oily” hydrocarbon type group).

A restless itch has now been scratched. I think I now understand why fresh ceramic pan coating can have such fine non-stick properties, and perhaps why they might be vulnerable to losing their non-stick properties. With Teflon type pan coatings, it is plasticky, oily Teflon all the way down, so if you abrade off a hundred molecular layers, it should make no difference. But with the ceramic coatings, it is not clear to me whether the oily Si-CH3 groups are only in the topmost atomic layer; maybe if that gets abraded off, there is only the quartz-like Si-OH groups to be found; or maybe there is a substantial (in atomic terms) topmost layer rich in Si-CH3 groups. Anyway, it makes sense to keep using oil when cooking on ceramic pans, to keep a hydrocarbon-type surface coating going there, and to avoid using metal utensils that can scrape and scratch the coating.