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Stainless steel knives are rusting

I have a set of stainless steel knifes made by Wiltshire which developed rust spots on them when I washed them and set them aside in the dish drainer. I was told by the company that they are metal and as such will rust if they are left wet. none of the other items in stainless steel that I have some of which I even use for storing water never developed this problem. The elementary school chemistry if I recollect it correctly says stainless steel was developed for the purpose of avoiding rusting of wrought iron. I might be outdated in my information about steel so I would like to know how rusting could occur in stainless steel items prepared for use in the kitchens. I would very much appreciate your reply.

Sujatha Chary
house wife - Sydney, NSW, Australia

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Hi Sujatha ! I bet that many other households have the same problem ... but there are different grades of stainless.

The 'better' ones will hardly every show any rusting but they are soft and do NOT take to a nice sharp edge. Typical are those with high class silver plated handles.

The 'other' ones may well, after some time, show some rust spots but can be easily sharpened and maintain a good edge.

As I'm the knife sharpener, I much, much prefer the latter so that when one slices a tomato, one can easily do so ... and to keep the knife 'clean', try some ultra super fine emery or better still the abrasive cloth that professionals use, such as stainless steel kitchen fabricators.

freeman newton portrait
Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).


First of two simultaneous responses --

Stainless steel is great stuff, but as the previous post says, it ain't perfect. Take a look at letter number 32430 it will tell you a few things about steel. The chromium does make the steel softer, but it also gives a very good resistance to rust and stains (your knife may just be stained from something). If this continues to be a problem just give it a light coat of vegetable oil after sharpening and cleaning, it's a good practice anyhow.

Marc Banks
- Elizabeth City, North Carolina

Second of two simultaneous responses --

The term "stainless" is should be "stain resistant" as most stainless steels will still rust in certain environments. As Freeman Newton pointed out there are many different types of stainless steels with varying degrees of stain resistance. Being a custom knifemaker I have seen just about all cutlery stainless steels(high carbon content) rust at one time or another.

One huge deciding factor in its rust resistance is the surface finish..a mirror polished piece of metal will be much less prone to oxidation than a satin finished piece. The coarser the finish the faster it will corrode. after removing the rust, to prevent another occurrence just dry the piece off from now on and maybe oil oil will work fine.

Jason Aube
- Flint, Michigan

Q. I have the same problem, my Tupperware knives rust if left wet but my cheap stainless steel knife (Woolworth's Brand) doesn't have one rust mark on it. So I have no idea why the cheap one doesn't rust compared to my expensive Tupperware set.

Ivy W.
- Australia
April 18, 2012

A. Hi Ivy.

There may be several different issues at play here. The most rust resistant of the common stainless steels (18/8, 18/10, type 316) cannot hold an edge at all. The next most rust resistant type, Type 304, can't either. I don't know, but I'd guess that your Woolworth knives are type 304.

Cheaper stainless steels, like the 400 series, hold an edge much better but are prone to rust spots. I'd suspect that your Tupperware knives may be 400 series.

Rust resistance is not the only quality that anyone wants in a knife. The very best knives aren't even stainless steel at all because the toughest materials and best at holding an edge aren't stainless steels.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
April 19, 2012

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