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As you’ll have seen we have just released our Ceres Deep Fryer Cleaner and Restorer and, as part of this, we carried out much research, both theoretical and hands-on testing. 

In our tests, we saw pans that ranged from being sparkling clean and featuring light carbon to ones with ‘wet’ carbon and hard baked-on carbon, but the most alarming was one with carbon covering corrosive pitting. 

It’s worth noting that pitting of this style rarely happens to stainless steel, so when we talk about pans, we will be talking about mild steel pans.

To make it clear, when using Ceres Deep Fryer Cleaner and Restorer most types of carbon are removable with a cleaning schedule in place, but carbon covering pitting is a dangerous area. 

We have seen different types of pitting, and in our view, you need to talk to your range manufacturer as soon as possible. They will check to see if you have any gas or pressure leakage and advise whether it’s okay to carry on using the pan in question. 

Our concern from a frying point of view is that the pitting will cause your oil to break down faster and the product you fry won’t taste as clean. 

We washed a pan that had pitting and every time we rinsed the pan with fresh water, the water turned dark black. 

What is pitting?

Pitting corrosion is a localised form of corrosion by which cavities or holes are produced in the material. Pitting is considered to be more dangerous than uniform corrosion damage because it is more difficult to detect, predict and design against. Corrosion products often cover the pits. Even a small, narrow pit with minimal overall metal loss can lead to the failure of an entire engineering system.

Pitting corrosion, which, for example, is almost a common denominator of all types of localised corrosion attack, may assume different shapes. Pitting corrosion can produce pits with their mouth open (uncovered) or covered with a semi-permeable membrane of corrosion products. Pits can be either hemispherical or cup-shaped. 

Different types of pitting

Undercut Pitting

Vertical grain attack


Shallow, wide

Narrow, deep


Horizontal grain attack

How does it happen?

I am not picking on any frying range here as pitting can happen to all of them. I believe entirely that deep frying pans take abuse like no other metal: they have a vast amount of direct forced heat on the underside, oil within the vessel can reach 180°C while chip pans (especially in round pans) fluctuate in temperature massively.

When the food products, fatty acids, starch, etc., stick to the bottom they can burn. If you don’t clean it at the same rate of carbon build-up, at some point localised pitting will occur. My non-metallurgy brain tells me this will happen a) where most the heat is and b) where most of the carbon settles.  


My concern is that if you have pitting, the pan might be ‘safe’ for now. But the question is how long for? If the pits get more prominent, wider or deeper without you knowing, at some point you will have a major failure. Would your insurance cover a major accident down to pitting of a pan?

Besides all the extreme cases, I am not sure frying in a pitted pan will give you the best results. Your oil will definitely spoil a lot faster due to being exposed to the broken down metal, and what we don’t know is how this could impact customers health.

If you have any pitting or cracks in your pan, call your range manufacturer today.

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